You should really come up with a name on your own.  Better that way, especially if you're trying to eventually get into casting.  Here is some basic advice along those lines.

Standard approaches people take seem to include making words up or citing specific things like their favorite character or something like that, but something you want to be careful of is picking something copyrighted.  In that case, if you ever became popular as a caster you could end up being forced to change it to avoid brand confusion.

Also, avoid naming yourself something you'd be afraid to say in public or you'll become a caster who can't ever tell anyone that he is a caster.  And who'd want that. ;)