when i slide the brighness scale to the bottom and back up again its brightens up....but still its not the brightest...
That means it can change brightness... The slider only goes to r_gamma value of 2, you can try typing "/r_gamma 3" in console (open with ~ key, below Esc; 3 is the highest value). Although that might cause the colors to seem washed out, so if you really want the problem solved:
What operating system? (Windows XP/Vista/7 ?, Mac? Linux?)
Did you install any graphics drivers? What graphics card do you have?