Take your stencil and peel off the layer of plastic on the bottom, from top to the bottom and place it where you want it. If your gun is uneven in the spot desired you need to run your finger on the the crevices and lay your stencil down slowly. Repeat this for other uneven spots. Next, mask your gun with scotch blue tape and make sure that their is no exposure to the parts of the gun not being spray painted.