Welcome chunk-style.... Well I see you either figured out how to change your name on your own, or an Admin helped you with that. As far as moving your music from iTunes to here I'm unsure. If you have your music in a folder on your computer you'd simply upload them to the site here.
How you'd do so is on the main page click 'Music showcase'
Select which genre/style of music you feel your song best belongs to.
Then next click 'New Topic'
Enter the name of your song on the Subject: line
Next enter any info you wish about your song, the duration of it, style, just anything you wish.
Next click ' Additional Options '
Then where you see 'Attach:' click [Browse]
Find the song you want to upload.
When you're satisfied and feel you have inputted all of the info for your song click ' Post '
I hope that was of some help. If not hopefully another member/Admin can help you out.