In order to get your own cell phone plans you have to be at least 18 years of age, at least with post paid. You might see if your parents will add you to their account or consider a prepaid account.
I think you might need to be 18 to get into a 2 year contract and you need to have credit. Or else you will need at least a $500 deposit. If not you are stuck with doing a Pre Pay plan. Have you considered other companies like Boost, metro Pcs?