If you are already listed on this team with limited access, you go to your Control Panel and click the link next to this team that says "Request Update Access." This will allow you to email members of this team who have update access so they can change your access level.
If you are not connected to this team already, go back to your Control Panel and click the link for "Add Team." If you want more information on this process, please review the FAQ on the Control Panel screen.