At this point, you should be pretty comfortable with setting up basic animations and interactions in Kite. However, everything we've done up to this point has been focusing on interactions within one screen. Just about every app you make will have more than one screen though, and you'll need to mock up the transition.
Creating screen transitions on one canvas seems confusing, so it really helps to break up the transition into logical chunks. In this case, the nav bar is considered a separate element from the screen - much like it is in actual implementation.