How to get a guy to want you?

I like this guy, Gregg, and he has a GF named Casey, but i really like him anyway. I text him alot, and i've told him i like him, but when i try to have a convo via text w/ him he just replys with "ok" and "bye" i really like him, and i want him to be mine. But i dont know how to really get his attention, shud i send hawt/sexy pics? thanks for the help