How do i subtley let him know....?

You should definitely flirt! Look up some flirting tips on cosmopolitan.com or cosmogirl.com. If he likes you back he'll flirt too, but be careful because some guys just like to flirt. If your unsure if hes one of these, pay attention to how he acts around other girls.. but not in a creepy way :p Be subtle at first with your flirting but as you get more confident be more direct so there'll be no doubt in his mind. Good luck.. !