(Hope this is okay to post here...)
I took this from some other RP forums that I hang around in. Basically you post a song that fits your character, or another person's character if you wish. You could also post themes for canon characters if you wish. You could also post songs for groups of characters, or to describe a certain stage of your character's life. There's really no set rules, so just have fun.
Wataru Kurenai/Kamen Rider Kiva - Destiny's Play
Destiny's PlaySpyro and Cynder theme -
Guide You Home