Jim to my Pam???

Hey guys, so here’s the deal. I met this guy through a common interest and he’s always been extremely attractive to me. But a few months ago I had this moment of ‘holy crap he’s going to be a really big part of my life someday...’ and slowly I’ve fallen head over heels. But he in no way likes me. He recently started dating one of my best friends and I’m doing my best to be happy for them because damn she really lucked out on him. I feel like at some point I should tell him how I feel. But how?????