User Activity

How does one become 'private' and identity is not shown? As in Private listing- bidders identities protected. Do you have to do something special to get that? If yes. What would it be?!?
Not being a big buyer l need help when it comes to 'feedback'. My question is about me giving 'feedback' to a seller. This seller won't leave 'feedback' for me until after l have posted 'feedback' for them. The 'seller' got their payment right after ...