Soundproofing apartment floors?

I need to soundproof the floors in my bedroom in my apartment. I thought about building a "floating" floor over the carpet/floor that is already there. I have also been wondering if there was a way to take up the boards without messing up the carpet so I could put soundproofing foam or something underneath the wood. I just don't know what to do. I need something easy and cheap to do. Any ideas??? I am very poor... and my neighbors get quite loud... and I am honestly just sick of walking on my HORRIBLY squeaking, creaking floors myself. Thanks!