If you wanna make it causal just text, "Hey, I like you, wanna hang out sometime?". Or do it in person, if you're confident enough. If he's not cool with it, he'll tell you. Just brush it off, if he does.
Don't do it in a text!
its best to just tell the person u like him, i live in regret for not telling this person i liked and still like 15 years later and still wish i had of told the person... so just do it....
talk to him on the phone or in person... over text just isn't the same or nearly as satisfying
i want you to know something but i dont know how to say it so just read the first three words again