You will need a quality overflow box, an internal water pump, and plumbing.
Basically the pump sits in the sump and pushes water up to the tank. The tank overflows into the overflow box and the water cascades down to the sump, etc, etc. The sump can house all your heaters, dosers and skimmer.
Draw it on paper and then come back with questions.
FYI - I use an external pump but my sump is drilled for it. External pumps don't add as much heat to the water but they have more failure points.