HTC EVO 4G :: Relabeling Names Of Artists And Songs?

I can't figure out how to relabel the artist and song names of songs that I downloaded. Because they are all messed up with numbers and dashes instead of them being under the correct artist and album art it is just throwing a majority of them under unknown artist. Also how do you properly label a song so it shows up with the artist and song name? For instance a file all messed up says 03_Marylin_manson - Sweet dreams_mp3.mp3 when obviously I want the song labeled simply: Sweet Dreams under the artist Marylin Manson.