I have this friend I want to get to know better, but....?

but we work together and we have been out once nd had a great time. We are keeping the relationship a secret at work and so far so good. I am having alot of dificulties trying to get this girl to open to me. When she calls on the fone she says hi and thats about it. When we first went out I had to grab ger hand at the movie in order to break the ice. She makes me feel so foreign to her and I need to know what I need to do to get her to be able to speek freely to me. She is black and I am white, but I don;t think that is the problem. I see her talk with her friends out loud at work and be herself, but when she is with me it is a nother ball game. I realy like this girl and for some reason I cant stop trying to win her over. I have never felt this way for a female and this is the first time. It is not because of here body, but it is because of her mind. When I am looking at her and she does not know it I see who she realy is.