simple you can download winrar (
http://www.rarlab.com/download.htm)and the program will extract the files in any rar zip or archive file supported or just open the rar file with the program and drap and drop the iff files to your nba2k9 folder and it will ask you to overwrite it now you can either choose to backup the original file before dragging the new one in or you can just overwrite it, you should make a shortcut on your desktop so you wont have to go looking for it everytime, so try that out it should work
hope that helps