First I get a gif that I like and I crop it around the place I want to be shown in the stamp. Then I resize it to fit the middle of the stamp I'm using. After that I over lay the gif on the stamp template and place it right. That's it really. It also depends what type of stamp template your using as well. Some stamps temples can only be used on Photoshop. Others you can just overlay gifs/images on them(example ahmed-art.deviantart.com/art/S… . Since I don't have that I just use 2 different websites instead.