Play on the lobby

After starting TripleA, click on "Find Games Online on the Lobby Server". On the Login Screen you have two options:

Create Account, using the Create Account button
login anonymously choose a username that hasn't been taken so far, then switch "Login Anonymously ?" on. You will no longer be required to make an account, but anyone can login with the same username.

On the lobby, on the right side you can see all the users currently online. Some of them have a comment near their username (such as afk=away from keyboard etc) to set a comment near your username, click on "Status" located on the bottom right of the screen. If you have a partner that is online, you can call for his attention by "slapping" him (right-click on their username on the right of the screen and click on slap He will be noted that you slapped him even if he is in a game. Other users will not see the "slapping")

on the bottom left it's a messenger type window. You can post messages there.

On the top left side are listed the current games. At Status you can see if game is in progress or host is waiting for players. To join a game, select a game from the list and click "Join Game" from below the list. You can watch other people's games and learn from them. Rarely games are protected by passwords.

You can host a game by clicking "Host Game". In the "comment" field you can write a comment such as game options or your level of experience on that map to find appropriate partners.

If you can't host, it's most probably because of your router. It can be solved by changing router settings and open a port (port forwarding).

Politeness

Generally players like to win. If you are losing, it is nice to give them satisfaction by not abandoning. Surrendering and telling them they play well is an option.

However, it's nice to surrender when you no longer have any chance of winning and game gets boring.