There's nothing wrong with telling someone that you have an interest in them. If they don't share that interest, it'll feel awkward for a bit, but the world will NOT end. Besides, either way, you'll have some practice for the next time you want to tell someone you like them.
Take a chance. A few options for sharing your feelings include:
1) friend him on social media then message him or send him a song that communicates what you want to say
2) write him a note
3) start sitting with him at lunch or another time when you can talk privately
Keep in mind that complimenting him, smiling at him, and maintaining eye contact will communicate your interest. See if he returns your attention. If so, you can say something as simple as "I think you're a special guy, John" or "You're awesome, John."