In the top left corner of your Me tab, you can see a circle with a colorful picture in it. This is your profile picture, or “avatar.” You can tap on it to change it.
If you use a free version of Hopscotch you can choose another image from these pre-made pictures:
Or, if you subscribe to the premium version of Hopscotch you can add your own custom profile picture. You can drag to move the image and pinch on the image to resize it: