Okay, let's get started...
First, enter the game lobby by clicking the Play Games button on the homepage. The Gathering Place is the where you can chat with other gamers, see their play stats, and launch games.

Once you have entered The Gathering Place you can start your own game by clicking the Create button and selecting the game you would like to play. Or, if you see a game table that has a status of Open, it is waiting for players, and you can join the table by highlighting the table listing and clicking the Join button.

If you've created your own game you can now adjust the settings to your liking. Settings are game-specific but generally follow the same basic format across all games. If you've joined somebody else's game, they are responsible for the game settings.
To play by yourself in games with "Solo Play," set the number of players to the total number of players you want to have at the table and the GTO Server will fill the rest of the seats with artificial intelligence players ("AI" players). Not all games have a single-player option.
Finally, click the Ready box to let everyone know you are ready to play. If you created the session, you need to click Start Game once everyone is ready.

Once you've started a game, it make take a few moments to a minute or more to load the game, especially if this is the first time you've played this game.
Because different players have different connection speeds, not everybody will show up in the game at the same time. Don't worry, just give it a minute, or use the lobby chat to make sure that the missing player(s) haven't experienced connection problems on their end.
TIP: While downloading a game, the download window will sometimes say "Download Stalled". This doesn't indicate a problem with your download. Just wait and your download will finish up.
Okay, now you're ready to play your game. On to Game Operations >