Here is the link for the proofreading group. First you need to hit the tab to join the group, then you'll see a tab to "Send Message to Group." Send your message about needing a proofer and leave your email address for proofers to contact you.
If you're looking for more work, don't forget to hit on the Cover Depos tab on the top of the main page, hit the red dot on the map where you'll cover work, and then click on the tab to "Join the Group." Once you do that, your email address will be saved with everyone else's email address and you'll receive email blasts of jobs in your area. You just contact the agency directly from the email with their contact info.