Internet

First off, there are no dumb question esp. when it's concering Android!

So... with each phone it is different but you can turn off 3G when you don't need it by going to settings> wireless and networks> mobile networks and unclicking data enabled. That will turn off your 3G if you really want it off. But if you are just looking to save money make sure your wifi is turned on when you are around a network you can use. I find it really helpfull to have a shortcut button on my homescreen. To add one, long click on your homescreen till a context menu pops up and then click on widget. You should see a "on/off wifi" button. Click on that and then you have a button to either turn on or off your wifi when you want it.

You can also download a data moitor from our app center, which should give you a better handle on how much data your phone is using.

Hope that helps!