How do I change my visible name?

Hi all
I'm excited to start sharing music here (you're of course welcome to check out my stuffcheck out my stuff...!).

I was wondering; After I already got a track approved, what if I want to change something in the tags? How do I do that?
Second question, as you can see I currently have a 'silly name'. I generally wouldn't mind; I like silly names :-)
But I'd rather pick an artistic name, and not my own.
How do I do that?

Thanks a mil!