Many watchOS apps (like Activity) have several pages which you could simply scroll between them, which is a very good way to use Apple Watch.

To create a page based navigation, Ctrl-Drag from one controller to another, and select "next page", as shown in the following picture:

Many watchOS apps (like Workout, Weather, Music, etc) have a main WKInterfaceTable or a set of buttons which are hooked up to another controller, similar to the navigation on iOS. This is called hierarchical view structure.

To connect a button, Ctrl-Drag from the button to a controller, and select "push" or "modal" based on your need, as shown in the following picture: