Joining a public tribe
Click on the left-hand hamburger menu and select Tribes from the drop down. Here you'll have an overview of Tribes you've already joined under My tribes, or you can explore new Tribes within Categories.
Joining a tribe you've been personally invited to
Joining your company's tribe
If your company has provided you with a Corporate Tribe, you should receive a link to a tribe landing page via your corporate email. Visit this page on your phone and follow the link to go straight to your tribe.
You can also create your own Tribe.