When you successfully login, you typically are greeted with the session overview page.
If you get a session invite from your DM, you'll skip this screen and go straight into game
On this page you can see which sessions are ongoing. The sessions you DM are shown with just their title, sessions you are playing in are shown with both the DM's name and the session title.
If you want to DM a game you can create a session here as well.
The bottom left button is for the account settings where a user can add an email, change password, or even delete their account.
The bottom right button is to Logout