I sent you a message below when you first signed up for CSRnation. You will "get an email blast of work in your area." That's how you find out what work needs to be covered, you'll get an email of the job offer. Contact the agency directly from the contact info on that "email you'll receive."
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.