With respect to this guy, nothing. You took your shot but it didn't work. Now you have to leave him alone until the awkward dies down.
Going forward when you find yourself liking somebody spend time with him. Flirt your tail off. Laugh at the jokes. Toss your hair. Touch his arm. Sit too close etc.
One of my favorite techniques to gage interest would be to inform the crush where you & your friends will be on a weekend night. Invite the crush & their friends to show up. If they come there is interest there. However, you have to see how they behave. If they immediately start hitting on your friends or someone else, then you know they do not see you in a romantic light.