The more you rep people, the more your rep power goes up.
(that is if you are referring to the rep power shown under you details in each post).
That just shows how many rep points you give to someone if you rep them. So
for example if Magents reps a person they will get 183 points.
Your total rep points received can be found by clicking on settings then scrolling
right to the bottom of the page. For every 100 rep points you get, you
receive another green bar under your name.