How do I turn my platonic relationship into a romantic one?

I'm a guy and I've been friends with this girl for ten years. We developed a friendship after she learned of my crush on her but she just wanted to be friends. I am and was cool with that. It's been about 8 years since I tried to make her my girlfriend. She has had boyfriends but nothing serious or long term. She has been single for the last three years. I want to try again but I'm very inexperienced with women. When it comes to this girl it has seemed to be a love at first sight thing. We hang out every once in a while and email constantly. I want to try to make her my girlfriend and be in a serious relationship with her. I'm not looking for sex I'm looking for her love. I know about dressing nice and crap like that I need to know how to pounce. I know how to be friends but I want more. I would do anything for this girl. I don't just go and say "hey want to be official" or something like that. What do I do? How do I do it? Where and how soon can I do it? What kind of occasion do I do it? I'm 22 she is 21.