Tampon help please!?!?

Okay so it's my first time and I'm super scared. My mom really wants me to use them since its summer and all but I'm nervous.. I've tried and I can't seem to get it even half way in. I've tried squaring and putting one leg on the toilet and nothing works! When I try to do it, it goes not even half way in and it hurts. Is it hopeless? I'm 15 and I know most girls my age use them but I'm guessing its too soon for me to attempt it.