Internet Usage on Samsung Galaxy Ace 5830. My provider gives my 3GB of data and I don't know how to find out how much I have used or have left.  Where can I find this information
Assuming that you are using a Galaxy Ace with Android v2.3 (Gingerbread), I suggest you to use an application like 3G Watchdog or Onavo Count. But if you are using a Android phone with Android v4.0 (Ice Cream Sandwich) or higher there is a built-in option in settings menu called "Data Usage".