To start a new game in Steam, open the application, go to your library, select the game you want to play, and click on 'Play'. Follow any prompts to start a new game session.

To join multiplayer games, navigate to the game’s main menu, select 'Multiplayer' or 'Online', and choose a game type. You may need to invite friends or find public matches to join.

Most games have an auto-save feature. To manually save, check the game menu for a 'Save' option, or use designated save shortcuts if available. Always confirm your progress is saved before quitting.

You can usually communicate with others via text or voice chat options in the game. Access the settings menu to configure your chat preferences and ensure that your microphone is set up if using voice chat.

To add friends, go to the 'Friends' section, click 'Add a Friend', and enter their Steam ID or email address. Once they accept your request, you can invite them to games. Here's how:
1. Open the Steam client.
2. Navigate to the 'Friends' tab.
3. Click 'Add a Friend'.
4. Enter their information and send the request.