Personalise your watch easily by changing the background picture of it:
To change the background picture, tap and hold on the start screen. To scroll amongst the pictures, swipe with your finger to the left and right. Once you choose the appropriate design for your watch, set it by tapping on it.
You can also choose a picture from your gallery to make the watch even more personal. To do that, swipe to the left until you see the option "Select a photo" in a blue rectangle. Tap on it, and choose your background picture.