The alignment is mostly just to add a little clarity on where you character stands, and no evil just because it's hard to make evil characters fit into a story where the good guys are in charge.
As for the alignment in the rules and what not, I'm not gonna be obnoxious and say Assassin's have to be evil or a Paladin HAS to be Lawful good. The alignment is just for flavor and to make everyone's motivations clearer.
As for your character looks good just include a background and alignment.
