This is another simple tutorial.

Apps needed:

-superimpose
-phonto

Open the template below into superimpose as a background.

Next open the image you want to go inside the phone. Tap transform and then hit the screen option. When you can see the image under the phone select mask and the erase. Instructions below.

Save to camera roll and open in phonto. Add your title and save to camera roll.

If you have any questions comment below!