A person's bidding is what he or she tells you to do for them. You do your brother's bidding when he asks you to bring him his shoes and you comply.
Doing your boss's bidding is usually part of a job description, although doing your cousin's or boyfriend's bidding usually isn't required — at least, it shouldn't be. When you are invited to eat at a friend's house, you might have to watch a slide show from his trip to Hawaii after dinner at his bidding. Bidding stems from the verb bid, with its Old English root of biddan, "ask, entreat, beseech, or order."