In my last shot, see the "create effect" in the lower right corner?
When you click on that, it will bring you to the three parts of the skin to add a texture. The button to the right of each part will allow you to open a file. You can then either choose an existing one, or open your own. The "file" dialogue is in the upper left corner- it is what allows you to save the new texture.
ID- you should make a tutorial