Replying to Help me decide

Hey, I am in a bit of a sticky wicket. There is this girls who I like and I am pretty shure she will say yes if I ask her out. I was planing to ask it to her face yesterday because we were hanging out all day. But sadly I never found the right time and didn't have the balls. Now I am in trouble, she is probobly expecting me to ask her out and she is probobly confused about why I didn't ask her yesterday. I am afraid if I wait until we hang out on friday that would be to long so how lame is asking someone out in a text message? Should I just call her? And finally I don't really know what to say (Hi will you go out with me sounds bad)