The complexity of the plumbing in a tank is usually dependent on a number of factors, foremost being what you want to keep and the tank, how big the tank is, and what kind of filtration you are going to use. If you have a large tank with only a few fish (or even a small tank with only a few fish) you could probably get by with only live rock and a proteing skimmer, which would require just a few tubes etc going out the back of the aquarium to something hanging on it. If you are using a sump, you will need a tube going down to the sump, one going back up plus the attachments for a proteing skimmer.
Mostly, I suggest that you buy a book about marine aquariums, specifically equipment, I have several, but I am not going to type out long passages