Another option other than Killyp's is if you just want to cut the beginning or end off a song you can do it in iTunes. Right-click (or ctrl click) the song you want, click 'Get Info' then find options at the top. Look for the start/stop time's and enter where you want the song to start/end. Click ok, right click the song again and covert it to MP3 or AAC, which ever you have available.
That should work. 🙂