I can't get an orgasm?

have you tried a vibrator? or finger?

I agree tightening the pc, the muscle you squeeze when you poop, will help you reach orgasm. I read that it works in both guys and girls and I tested it it really does. try G-spot message it can vary from girl to girl but sometimes its easier there than on the clit. also g-spot equals squirt and multiple orgasms. If I were you I'd consult this site.
PS. I spend to much time reading up on this stuff, but its intresting and helpful for when the first time comes

PSS: link

Don't give up! Just keep going and buy some lube. I also suggest playing with your nipples beforehand or during, usually that helps me along.

try some slow calm penetration, while you rub your clit, and use your PC muscles to clamp down on whatever you use to penetrate. Try a hairbrush handle or something similar so you don't have to focus on your hands and fingers and such.