[Edit] Set a picture as background in Pic Collage
1. Double tap/long tap the picture and choose "Set as Background" from the menu that pops up. (The cropping function is only available in Android now.)
Please refer to the instruction collage below.
2. (iOS only) Please select the Background icon. On the left of the scroll bar there will be an icon where you can add your own photo. Please refer to the instructions below.