How Do You Change The Background Of Your profile

I'm still kind of stuck in the dark ages....
I have NO idea in HELL how I meant to change it and I am SOOOO SICK of the mibba background.... HELP ME PLEASE???
And now since this needs to be AT LEAST one hundred words long I have to blabber a bit...
if someone would mind making me one?? One with My CHemical Romance maybe??
And did anyone know the number one selling item for mens fashion was the man bra (a real bra!!) for men (obviously) in Japan in 2009.... ha ha XP Amazing!!
I need to get one for some of my friends xD