You can buy retro fit lighting systems that you can then mount in your canopy . You need to have some fans in to move air to keep the lighting system cool . Depending on what kinds of corals you are going to keep will be helpful in picking out a lighting system as well .
I have a 36 gal bow front with an open top and run a Coralife 30" ( my tank length , I know what an odd size . ) 2 X 65watt PC lighting system with 2 Blue Lunar LED's . I was running 2 Current bulbs in the system but my 10k / atinic split , started acting up so I went back to the Coralife 10k bulb on that side . The other bulb I am running is a dual atinic bulb from Current .
Currently in the tank I have 3 different Zoanthids , 1 Powder Blue Palythoia , 2 different Xenia , 6 different colors of star polyps ,yellow polyps , moon polyps, 7 different mushrooms , 3 different Ricordia , & a Kenya tree
All seem to be doing well with the lighting . The zoo's like lots of light so I have built a rock platform high in the tank for them to live . Probably get better growth with a metal halide than PC , but they seem to live fine under the PC's .
Once you start adding corals you won't want to stop ..
Hope some of this is somewhat helpful ....