No, its not a supporter feature. Anyone can do it (you can only have one player ad at a time.)
1) Go to "Community" in the menu to the left.
2) Go to the drop down menu, and click on the last item on the list: "New Ad"
3) Choose "Transfer Ad" from the click menu.
4) Type your ad and click "Send Message"
P.S. If you can't find it, try this link:
http://www.buzzerbeater.com/community/newad.aspx