How can a Fitbit help me loose weight?

Hi! I got a Fitbit Flex for Christmas. It has been fun logging all of my data (calories, steps, sleep, etc.). Almost a game. But what really is the plan? I just seem to see “success stories” (or “failure stories”) on the web, but not a lot of real plans. Do I just try to stay under the allotted calories? Record 10,000 steps a day? What is the point? Or are we really just talking about providing metrics for a plan that doesn’t really have anything to do with the Fitbit. Thoughts?