i see how to create a game but i dont see how to join one. how do i do this?

If you have been invited to a game, you can just click on it and click the "Join Game" button.

If you're looking to play a pickup game, they will be advertised at the top of the My Games page. They usually fill up fast, so you may not see this if there aren't any. You can easily create one yourself just by creating a game and adding Open Seats to it on the last step.