Thanks for reaching out to us!
You can achieve this by:
1. Upload the photo with the face to the Photo Basket at the bottom of the editor and drag it onto your photo
2. Next erase the areas of the photo you dragged on (except for the face) by first clicking the Eraser button on the Photo Properties dialog that appears (above the Delete button at the bottom of this dialog)
We have a brief demo video outlining this process here. Let us know if you have any questions!
Regards – The Ribbet Team