Well maybe you can first try flirting more and see where that leads. I'm sure that you flirt a lot with him already but this time try to notice what you do and what he does in return. This is just to strengthen the bond you two already have. It also helps if you try to do a "social experiment" that involves looking into each other's eyes for about four minutes straight. This seriously works. You will somehow find each other more trustworthy and/or attractive. I did this with some people who I've liked and it works every time.
And as you go along, gradually you can talk to him about relationships. Just casually bring up the topic some time and see what he thinks about it. This could give you some signals to what he thinks not only about relationships but also the potentials of being in one. Hopefully he'll get the hints and see that you're interested in him. Also watch how he behaves towards you. You can look up the typical signs people display when they like someone and these are usually pretty general things that you can find on the internet.
But if you truly want to know for sure, just confess your feelings for him and see how he reacts. Make sure the moment is right and just tell him how you feel. There are signs that people give off when they like another person but those are not always reliable.
