Battle.net is the online server used by Blizzard to connect players online. Players on Warcraft III: The Frozen Throne can create clans, host games, join chat channels, add friends, and more.
Clans are generally a community of players with a common intrest, such as playing one type of game or a group of map makers. You can find a list of clans playing Gaias Retaliation here.
Chat channels are places where people can gather and talk to each other all at once.
Games are hosted by going into the Custom Game tab and creating a game there. You are also able to join or load a game. In order to keep getting a fresh list of games you need to use the Refresh button near the top of the screen.
Friends can by added by typing /f add (Name).
You can talk to them with:
- /w (Name)
- All Friends
- /f m