Griz1946

Hi folks; I recently acquired a Line 6 Spider IV 75 Amplifier and have no idea how to operate it yet. I do have a question though about playing MP3's through it. I would like to play backtracks on this amp but don't know how to go about it. Could I put the backtracks on a USB stick or must I do it another way? Thank you for any help with this matter, but I am totally stumped. Regards Bud