1. Open the image you want to make into a custom shape. In this example I'm using an image of a leaf. (SEE FIG. 1)
2. Select the outside of the image by holding down the Ctrl key (or the Command Key on a Mac) and clicking on the Layer Thumbnail. Youshould now have marching ants around your image. (SEE FIG. 2)
3. Select the Paths Tab, and choose 'Make Work Path from Selection' .(SEE FIG. 3)
4. Then all you need to do is choose Edit -> Define Custom Shape, and then name your new Custom Shape! Now you have your own CustomShape to use for any layout you like.