What you need:
1: 10 photots
2. Superimpose
3. Lockscreen image
1. Open superimpose
Hit the top left button and choose the lockscreen picture
2. Hit the same button>New foreground>
Choose an image you want
3. Go to transform and move the picture over one of the buttons
Hit the top right settings button and lower the transparency
4. Go to 'masks' and erase everything by going to the top right settings button and hitting the paintbrush button
5. Hit the same settings button>hit the eraser button> and cover the button with the picture.
6. Go to 'transform' hit the 'merge' button and do a the other buttons!