How to authorize computer for itunes?

How to authorize my computer on Itunes?

• My brother shair and itunes account. He downloaded a song on his computer and I would like to put it on mine also. Though when I go to re download it it says "Your Computer is not Authorized, you must authorize your computer before you can download previous purchases." Now... How can I authorize the computer???? I can't figure it out? Please Help, Thanks!

• Answer:

  Hi there, judging by the fact that you asked this question 3 days ago you probably figured it out by now. but just in case I'll tell how to do it. first open up itunes. On the top of the screen there should be the option that says "share." click on that and then there should be an option that says "Authorize this Computer." click on that and follow the rest of the directions. Hope this helped.