How is it damaged? Most likely you won't be able to recover files from it....
However, if you want to go ahead and try, just plug the drive in the IDE ribbon cable inside your computer. It's a flat cable that connects your motherboard to your CD drives, and your harddrive. There should be two connectors per ribbon cable, so just plug the damaged harddrive into one of the spare connectors on the ribbon cable, and you should be good to go.