An important thing to have in the Blog Shop world is a good reputation! Here is a quick tutorial on how to leave feedback, and check the feedback of a user that you are doing business with.
All user feedback has to be approved by the admins of this site for now.
1) After you have purchased an item from someone go back to that listing(or even another listing from the same user). On the right side click the “Poster” tab on the contact form. If you are on mobile, just scroll down until you see the “Contact” box.