Is this gonna tell her I like her?

Ok so I have become very good friends with this girl this year. But what she may not know is that I like her a lot all year. We went to a theme park together yesterday and had a lot of fun, now I realized after yesterday that I'm done, I can't take not being with her anymore. So I'm gonna try to say things to her that will make possibly get the obvious feelings that I like her and that I'm close to asking her out. So I said on Facebook IM, "it was really Cool hanging with ya yesterday" what should I say next that's gonna make her know I like her other than"like u" or "wanna go out"