From Team.biz you can login to all of the teams you are a member of. If you don't see the team in your app, just click the '+' button on the lefthand menu and add the team.
Once you've added your teams you can navigate between the different teams from within the app.
- Locate the lefthand navigate pane
- Click the team that you want to open
Need to create a new team? Instructions on creating a new team are here.