Affiliate Marketing Secrets

I just turned 18 at the beginning of this month and this will be my first time ordering my own new cell phone. I have a Droid now but I am getting an early upgrade and will be paying 20$ (I have Verizon) to get a free Blackberry Curve (it was pre-owned. Not refurbished though).
My question is, what does it mean when, on the phone’s page, it says “Phone Requires Data Package”?
It brings me to a page when I click on the link and it says this:
Monthly Data Allowance, Monthly Access Fee, Rate After Allowance
Pay Per Use – $0.00 – $1.99 per 1MB
(Basic Phones Only)
.
75MB3 – $10.00 – $10.00 per 75MB
(Basic Phones Only)
.
2GB2 – $30.00 – $10.00 per 1GB
.
5GB – $50.00 – $10.00 per 1GB
.
10GB – $80.00 – $10.00 per 1GB
.
So if I payed 30$ for 2GB what exactly does that mean? And would it charge me 30$ every month after that or would it charge me only 10$ every month?
Please help me out!
Thankyou to those that answer.