Making images transparent is useful when building when a site. Follow the following steps, and you should be able to make any image you want transparent:
1.) Pick the picture you want to make transparent.
2.) Select the area around the image until the entire area around the image has been selected.
3.) Fill the selected area with a color that is not in the image.
4.) Hit the 'Delete' button. This should clear out the selected area.
5.) Save your image as a .gif.

This should make any image transparent. :)