How do I get all my music from iTunes into Windows Media Player?

I just recently bought a LG Quantum, (Windows Phone) and I want to add music to it, because the music used to be on my iPhone. I want to take all the music from my iTunes library (NOT bought from the iTunes store) and put it in Windows Media Player on my Windows 7 laptop. I'm not exactly "computer savvy" so please break it down. Thank you!