I want to remove some songs from my ipod

Question

I bought a Apple nano 4th generation 8GB ipod at a pawn shop. It didnt have anything on it. It didnt come with any manuals or paperwork so I am unsure . When I atempted to add music to it, I didnt uncheck any of the music that my kids had on itunes..*yukk* so... Every song on my itunes was added to my ipod! I desperately need a manual. Can you tell me how to get one? I also need to remove all those yukky rap tunes from my ipod. HELP!