Clicking the digital crown on the side of the device takes the wearer to the "home screen," which is a terrible name for this interface considering it's not the first thing you see when you wake the Apple Watch. That would be the watchface, which shows you the time.
I never use the home screen to access apps, because pushing a button is like trying to play a game of Operation blind-folded. My very normal sized hands always fail to hit the right icon.
It's also impossible to organize the apps in a way that makes any sense. When you try to relocate one on the home screen, it shifts all neighboring icons, undoing your efforts.