You will also need the app Fotoffiti
How to get a Graffiti Stencil look with Fotoffiti App.
1) Here’s my original photograph (below, left). It is best to have a good contrast in your photograph so I ran the photo through Camera+ using the flash filter to add more light to the lighter areas.
2) Finally, open the image in Fotoffiti; choose a spray colour, shake your phone and you should get something like the result below.
Note….I love the effect of this app but it would be even better if you could remove the brick wall and choose your own background.