When i download apps on my iphone does it use data?

I just got a new iphone 4 today and i have already downloaded 6 apps. I only have 300megabytes of data and i'm afraid i have gone over my limit. The apps that i downloaded said at the bottom of the app store between 5-20 mg worth of data and i didn't know if that data counts towards my monthly amount i get or if the 5-20 mg is just how much space it takes up on my phone! Please tell me because i know i don't get alot of data each month and this is the first phone i have gotten with internet and my mom will be pissed if i have gone over the limit!

That's how much room it takes up on the phone, but here are a few tips-

If you're downloading over the 4G/3G system then it uses your data. If you use Wi-Fi, it doesn't use up your data plan. Your iPhone will work with your home network (go into settings & turn on Wi-Fi. If it detects your home network, tap on it.It'll then ask for your password, which can vary depending on your ISP.AT&T has it on your modem, other services either assign or let you choose a password. If you're not sure, ask your mom for the password. Once your iPhone is on the home Wi-Fi, you can use it all day long without worry. If you have Wi-Fi, there'll be a cone-shaped symbol after the AT&T/Verizon/Sprint logo)