I can't get this girl out of my head.
Would you go out with her if she asked you out?
Yes I'd think that would be something really worth trying.
Talking about your romantic interests with others is a good thing as it can help you be more grounded and in tune with reality. Having a crush is fine but sometimes people can get too caught up in fantasy. It's good to talk about your thoughts and feelings with others as they can offer a valuable outside perspective.
I don't know how to talk with her and I'm afraid to ask her out.
Give it a shot, you never know, she might like you back! You won't know until you try.