How exactly do you "ask someone out?"
If it matters, this is how I think my situation will play out.

Me:Ummmm...*****.
Her: ::Turns around::
Me: (This is the part I need help on. What do I say?)

Ask the person if she would like to join you for lunch or something and that you would gladly pay for her meal. This usually does work. Also, if you want to stop a girl in her tracks so you could get to know her, ask her for a minute of her time. Maybe then you could progress forth.

you:ummmm*****
her:*turns around*
you:*looks deep into her eyes and says* i have always loved you, so i am asking you out on a date right now

its worth a try eh, i am pretty sure it will work

Also, I've never talked to her...

first try to be a friend say what you would say to a friend. that way you will get worm up to talking to her. then ask her in a joke like " would it be funny if we were going out" then you will see what she thinks about it and then you get your answer. it will be easyer to ask her out or not. thats the easy way to do it but other then that slip the question in. but try not to you the same ex i used with " would it be funny if we were going out" because that not as funny as what you can do on your own.

Pure confidence... psyche yourself out - self-hypnosis.

Do it directly and confidently, say it like it is - rejection is part of the game(no one told you?).