First you'd need a way to remove water from the display to the sump(I use dual 700gph LifeReef overflows)...second you need to purchase or build the sump itself(I used a 29 gal aquarium and installed a series of baffles to create chambers)...third you need a return pump rated slightly lower than the GPH exiting from your display to avoid flooding...then of course you need the plumbing to hook it all up.
Not a very complicated process...and as mentioned above try a search for sump or something close and you'll likely find a ton of info.