How do I keep track of data usage on the iPhone 5C?

I just purchased an iPhone 5C (my first smartphone), and I'm confused as to what exactly the GB information in the "Usage" menu under Settings-->General-->Usage means. Are those gigs that are listed how much I have used and available for storage ONLY, or does it also include LTE data usage? I just synced my phone with my iTunes library on my computer, and my "GB used" jumped from 1.0 to 6.3 GB. It seems to be under the heading "storage" and says I still have 7.0 GB available, so I'm inclined to think that it is only counting what I am actually storing on my phone, but if that is the case, then where can I check how much of my data for the month I have used? I am on a family plan, so I want to make sure I'm not accidentally driving our usage up. My Wifi connection at home is currently out, so I know I was using some LTE this morning, but I don't think it was very much. I figured out how to turn off LTE and 3G so I'm not accidentally using data now, but in any case, does anybody know where I can find my data usage info on my phone?

Thanks!