diff --git a/src/main/java/com/university/chat/Server/ClientSession.java b/src/main/java/com/university/chat/Server/ClientSession.java
index f09d64a..227bba4 100644
--- a/src/main/java/com/university/chat/Server/ClientSession.java
+++ b/src/main/java/com/university/chat/Server/ClientSession.java
@@ -2,62 +2,145 @@ package com.university.chat.Server;
 
 import com.university.chat.Common.ChatMessage;
 import com.university.chat.Common.FileMessage;
+import com.university.chat.Common.MessageType;
 
 import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.net.Socket;
 import java.nio.file.Files;
 
 public class ClientSession implements Runnable {
 
     private String username;
+    private Socket socket;
+    private final UserManager userManager;
+    private ObjectOutputStream out;
+    private ObjectInputStream in;
 
     public ClientSession(Socket socket, UserManager userManager) {
-        // TODO : Create an ObjectOutputStream from socket.getOutputStream()
-        //         and an ObjectInputStream from socket.getInputStream().
+
+        this.userManager = userManager;
+        this.socket = socket;
+
+        try {
+            this.out = new ObjectOutputStream(socket.getOutputStream());
+            out.flush();
+            this.in = new ObjectInputStream(socket.getInputStream());
+        }
+        catch (IOException e) {
+            System.out.println("Error initializing stream: " + e.getMessage());
+        }
     }
 
     @Override
     public void run() {
         try {
+            System.out.println("welcome");
 
-            // TODO: Welcome the user (login step)
-            //  1. Read the first object sent by the client.
-            //  2. Check it's a ChatMessage with type LOGIN.
-            //  3. Extract the username.
-            //  4. Try to register the user via userManager.addUser(...).
-            //  5. If the username is taken, send back LOGIN_FAILED and close the socket.
-            //  6. Otherwise, create the user's folders with FileManager.createUserFolders(...)
-            //      and send back LOGIN_SUCCESS.
+            Object object = in.readObject();
 
-            // TODO: Main message loop
-            //   In a loop, call in.readObject(), you can separate messages by their type:
-            //     - if it's a ChatMessage      -> call handleChatMessage(msg)
-            //     - if it's a FileMessage      -> call handleFileMessage(fileMsg)
-            //   Keep looping until the connection is closed (an exception will be thrown).
+            if (object instanceof ChatMessage login && login.getType() == MessageType.LOGIN) {
 
-        } catch (Exception e) {
+                username = login.getSender();
+
+                if (userManager.addUser(username, this)) {
+                    System.out.printf("Successfully registered: %s\n", username);
+
+                    FileManager.createUserFolders(username);
+
+                    out.writeObject(
+                            new ChatMessage(MessageType.LOGIN_SUCCESS,
+                                    "[server]",
+                                    username,
+                                    null
+                            ));
+
+                    out.flush();
+                    broadcastUserList();
+                }
+                else {
+                    out.writeObject(
+                            new ChatMessage(MessageType.LOGIN_FAILED,
+                                    "[server]",
+                                    username,
+                                    null
+                            ));
+                    out.flush();
+
+                    socket.close();
+                    return;
+                }
+
+            } else {
+                socket.close();
+                return;
+            }
+
+            while (true) {
+
+                Object msg = in.readObject();
+
+                if (msg instanceof ChatMessage chatMsg) {
+                    handleChatMessage(chatMsg);
+                }
+                else if (msg instanceof FileMessage fileMsg) {
+                    handleFileMessage(fileMsg);
+                }
+            }
+
+        } catch (IOException | ClassNotFoundException e) {
             System.out.println("Disconnected: " + username);
-        } finally {
-            // TODO: Remove the user from UserManager so they no longer
-            //        receive broadcasts or appear in users list
+        }
+        finally {
+            if (username != null) {
+                userManager.removeUser(username);
+                broadcastUserList();
+            }
         }
     }
 
-
     private void handleChatMessage(ChatMessage msg) throws IOException {
         switch (msg.getType()) {
             case PUBLIC_MESSAGE -> {
-                // TODO: Broadcast this message to every connected client.
+                Iterable<ClientSession> users = userManager.getAllSessions();
+                for (ClientSession user : users) {
+                    if (user != this) {
+                        user.sendObject(msg);
+                    }
+                }
             }
             case PRIVATE_MESSAGE -> {
-                // TODO: Forward this message to the receiver user.
+
+                ClientSession receiver = userManager.getUser(msg.getReceiver());
+                if (receiver != null) {
+                    receiver.sendObject(msg);
+                }
+                else {
+                    sendObject(new ChatMessage(
+                            MessageType.PRIVATE_MESSAGE,
+                            "[server]",
+                            username,
+                            "User not found: " + msg.getReceiver()
+                    ));
+                }
             }
             case USER_LIST -> {
-                // TODO: Reply to the requester with the list of online users.
+
+                sendObject(new ChatMessage(MessageType.USER_LIST,
+                        "[server]",
+                        username,
+                        userManager.listUsers())
+                );
             }
         }
     }
 
+    private synchronized void sendObject(Object obj) throws IOException {
+        out.writeObject(obj);
+        out.flush();
+    }
+
     private void handleFileMessage(FileMessage fileMsg) throws IOException {
         // Storing the file
         var sentPath = FileManager.getSentPath(fileMsg.getSender(), fileMsg.getFilename());
@@ -66,6 +149,26 @@ public class ClientSession implements Runnable {
         Files.write(sentPath, fileMsg.getData());
         Files.write(recvPath, fileMsg.getData());
 
-        // TODO: Forward the received file-message to the destination user.
+        ClientSession receiver = userManager.getUser(fileMsg.getReceiver());
+        receiver.sendObject(fileMsg);
     }
+
+    private void broadcastUserList() {
+
+        try {
+            String activeUsers = userManager.listUsers();
+            ChatMessage updateMsg = new ChatMessage(
+                    MessageType.USER_LIST,
+                    "[server]",
+                    null,
+                    activeUsers
+            );
+            for (ClientSession session : userManager.getAllSessions()) {
+                session.sendObject(updateMsg);
+            }
+        } catch (IOException e) {
+            System.out.println("Error broadcasting user list: " + e.getMessage());
+        }
+    }
+
 }
\ No newline at end of file