How do you ask a girl who has been your friend out?

It's serious o!
A brother needs your help o, please to all guys and girls, how do you ask out a girl with whom you've been friends with for about 2 good years? How do you do it without hurting her feelings, or making a fool of yourself?

Ok,
let me explain further.
I've known this girl for about 2 years now. We met through a friend when we resumed our first year in the University. Since then we've been friends, we see in class, we chat on phone and advice each other.
But of late, I've been developing feelings for her and I don't know how to break it out to her that I want our relationship to extend a bit longer than just platonic friendship, I want her to be mine!

Please advice me and help me please! My main questions really are- where do I tell, when should it be and how do I start and end it in such a way that she'll fall in Love with me. I don't know if she has been before now. So please comment below to help.

By- A friend in School.