Unprotected file

I'm making a music video for Seagull and when I try to import the file from my computer (itunes) into Windows Movie Maker it says it has to be unprotected. I don't know how to unprotect files or convert them and when i try to download the programs to unprotect the files, the computer won't support them or something. Could someone please send me an unprotected file of Seagull? Thanks.