This is according to how my camera is set up, shouldnt be too differant from yours
1.Once your camera is on go to program, the P on your camera if it has 1, then go to your focuses, mine are (from left to right) macro, normal,manual....go to manual
2.Hit the FUNC. SET button, go down to the white balances(WB), then scroll until you find the fish,clickt the fish,and your camera is now in underwater mode, oferring better coloration for corals,fish,rocks,etc.
3.As you are still on the white balances clik the DISP. button, it should take you to a color square, blue on the left,green top,red right, and magenta bottom, move the dot around until you find what color you want
For example: My tank is red due to a red bulb, so i put my color on 1 blue one green,and it cancels out the red
4.Exit out and find whatever you want to take a picture of, click manual focus again, then scroll up and down until you find the right focus, if you get it exactly right your photo will look really really clear
5.Take your photo, change brightness if needed
For led shots follow the same steps but when you go to underwater mode go to Custom White Balance, set the whiteness to something at the top of your tank thats white
Also for led shots i do 8 red 1 green or 9 red color combo, depending on the coral
Hope i helped!