If you know someone who stretches canvas for paintings, have them help you with this step. There are several methods that can be found online to help you wrap the panel, but they can be tricky if you do not have a someone there to help.
We are currently working on a more detailed Instructable just for canvas stretching. Check back soon and hopefully this paragraph will be replaced with a link.
The point of this step is to cover the fiberglass and the wooden frame in fabric. If you have another method you'd like to use, feel free to do so.