Cyan is an example of this method. Also include what type of artists you are and any other details she might want to know. You can sign up as a staff member, contributor or fan artist. Staff members usually stay on for at least a month and produce artwork that is directly placed in the comic, with a little gallery artwork on the side. Contributors just submit one piece of artwork and then leave.
Fan artists submit as little or as much as they like and their artwork goes into the image gallery.
If you just want put in a little art and have something to brag about to your friends then be a contributor. Contra and Pronin are contributors because Contra just helped with the comic and Pronin designed the site. Both of them have now disappeared off the face of the planet.