What should I say in the message telling the guy I like that I like him?

I am going to send him a message, I am tired of being bottled up, I want to tell him to get it over with. I have never talked to him much in person, but we talked a bit on facebook not too long ago. Please don't tell me that I should tell him in person because i can't lol. And its not going to be really out of the blue, he stares at me sometimes, i catch him sometimes too. :P What should I say in the message. I just want to be straightforward.. sort of. :P thanks!!