Basically, on a predrilled, you get some hose clamps and open your durso box, stick the big ribbed hose on the "in" pipe of your sump, and on the drain of your downflow box (the predrilled thing), stick your return pump on one end of your sump, with a hose clamped on, [plastic clamp!] and that hose running up to the tank's outflow [which is in the downflow box, go figure] Stick the durso pipe into the only hole it will fit in the downflow, and you're plumbed, except for the skimmer. Stick that in the middle sump chamber, with its pump submerged, set up the collection cup per instructions, and plug in. If you get mh lighting, you'll probably supplement with actinics: you can get it all in one fixture, with two honking great ballasts: put all that on timers. If you go T5, it's a little less expensive and you can keep most corals, except the fussiest acroporas. [Colored sticks.]
Unlike freshwater aquariums, you do not have a 1) filter 2) lid [toss the sump lids: they're worthless.
Unlike freshwater aquariums, you have lots of crawley life in 'live' rock [rock that's lived in the ocean or salt water and has bacteria galore]---that does the job of your oldfashioned filter, and does it better.
Heat buildup and maintaining an even temperature are a challenge. Lids are anathema. If you have jumping fish, you just put a gridwork of lighting panel atop. It lets air flow.
Your lights need to be about 9 inches above your tank, and it's safest to have a glass shield under the bulb, so it doesn't get hit with a splashing fish and explode, taking out your corals. If you have a glass shield, you will want a lighting fixture that has fans. This is more expensive, but it is one headache removed.
