Wanting to buy new light bulbs for my fish tank, but have no clue what kind?

I have a 55 gallon fish tank, and have had it for a while. Bought it off some one and the light bulbs are old, and I need new ones but I have noooooo clue what kind of bulbs or light fixtures to buy. My lights I have now are dim. Please let me know what some good brands of fish lights to buy. It's for a standered 55 gallon tank, with two lights on each side of the tank. Thanks!