First you have locate the knob or the dial controls. This is what brightens the lights on your dashboard. Then you need to check the fuse that controls the dashboard lights. Most of the time the fuse needs a simple replacement.
There are several lights behind the dashboard. When some of them burn out you will get some spots that are brighter and some that are quite dim. Replacing the dash bulbs is an annoying process. It usually involves disassembling the dashboard and usually results in rattles or squeeks.