Setting up the Home screen
In the Apple Watch app on your iPhone, scroll down to find two group of apps. The first one contains Apple’s apps, while the lower block is where you’ll find apps from other developers. Third-party Watch apps are bundled with their iPhone app.
Tap on a third-party app in the list and turn on the Show On Apple Watch switch to install it on your Watch. Some apps also provide Glances, which give quick access to key features when you slide a finger up from the bottom of the watch face). You can enable up to 20 of them.
Apps are rearranged (and third-party ones removed) directly from the Watch’s Home screen. Tap and hold an app icon until all the icons start to jiggle. Tap and hold an app icon to grab it, and move it to a new position. To delete a third-party app (indicated with a cross at its top-left), tap its icon swiftly and choose Delete App.
It’s a lot easier to arrange apps in the iPhone app. Tap App Layout and drag app icons around to rearrange them; the layout on your Watch refreshes a moment later. Tap My Watch at the top-left when you’re finished.