You can navigate through Katch using App Bar, which you can find at the bottom of your screen. Or you can use the Main Menu, where you can see the title of each feature and Settings. Main Menu you can find just by clicking the hamburger button (3 lines) in the bottom left corner of the App Bar.
In the App Bar you can find buttons (left to the right):
Main Menu My Videos Page User Profiles Katch Events My Messages