How to know how much data i have left on my iPhone?

I got an iPhone 4 3 days ago and my data plan is 2GB with verizon. And I checked my data usage and it says I sent 1.8MB but I'm new to all of this and I don't even know how much Data that is or how much I have left? Or what?

If you used 1.8 mbs you have roughly 1.8 gigs left
i think verizon has a application for that
to let you know when you come close to data cap

The data is controlled by your plan with Verizon. Call them for the easiest way to determine your usage on a regular basis. I have AT & T and there's a 4 digit number I can call free of charge. It's really easy. I'm sure Verizon has something similar.

Let me give you a break down on what the terms "MB" and "GB" mean.
1 GB or gigabyte=1, 024 MB
So, if your plan includes 2GB, that equals 2, 048 MB.
If you have only used 1.8 MB, you have almost your entire data plan allowance left to be used.
You can check your data usage by doing entering #DATA on your keypad (#3282) and dialing like you would a phone call. It should then text you back with your current usage.