you wanted to know and more about establishing and maintaining a saltwater
1) buy a tank.
-30 gallons the absolute minimum you can get away with. anything smaller and it will be highly unstable and even a longtime hobbbyist will have trouble. a tank of at least 50 gallons, however, is extremely highly recommended. (most people who start with a 30 upgrade within a year and a half.)
-get it from a decent fish store. do not, i repeat do *not* buy a tank from petsmart or petco. their tanks have just enough filtration to keep freshwater alive with difficulty. saltwater, don't even *think* about it. any tank over 55 gallons or so should really have a wet-dry filter, or at least two power filters with bio-wheels. anything over 75 must have a wet-dry.
2) add salt.
-fill tank 1/3 full of water. tap is fine.
-add salt *slowly*, making sure it dissolves. gradually alternate additions of salt and water.
-top off tank with water. NOW add gravel or crushed coral. hook up filter and let run at least 24 hours.
1) buy damselfish. one per five gallon of water has been found to be just about the perfect recipe for success. 55 gallon tank = 11 damsels. 120 = 24. and so on.
2) overfeed fish. at least three times a day. make sure extra food hits the bottom. if any damsels die, leave the bodies in the tank.
3) take water to local store to be tested once a week. over time, your ammonia will spike up, then the bacteria that break down ammonia will multiply and the ammonia will go down. as the ammonia goes down, the nitrite will go up. (ammonia is converted to nitrite). the nitrite=eating bacteria will then bloom as well, and the nitrite will go down. when both ammonia and nitrite are at zero, your tank is cycled.
now, before you add *anything* to the tank besides your already existant damsels, you must decide what kind of tank you want. your three options are this:
predator tank: large agressive carnivores such as lionfish, triggers, small eels and sharks, foxfaces, pufferfish, and grouper species. number of fish per tank is limited as the fish are quite territorial and not above taking a chunk out of a tankmate when they consider the place too crowded.
fish-only tank: this tank offers the largest selection of fish. almost all fish not considered predators can be kept in this tank. of course, as with any fish, too-large animals will munch on smaller species. fish not conisered reef safe can be kept in this tank. major angels, dwarf puffers, hogfish, butterfly fish, and tuskfish are some species safe for a fish-only tank, as well as *all* reef-safe fish.
reef tank: a tank with fewer fish but loads of live coral, anemonaes, and an assortment of invertebrates. choice of fish is somewhat limited as many marine fish have a natural diet of coral and sponge and will munch your pricely masterpieces given the chance. marine bettas, clownfish- yellow/purple/sailfin/blue/yellow-eye tangs are safe--but with any tang species, have one of a kind, or at least four. otherwise they will fight--minor angels, specifically the flame, coral beauty, and potter's angels are safe as well. other 'minor' fish include dwarf hogs, small gobies, mandarins, and firefish, as well as pseudos and grammas. starfish, snails, crabs, shrimp, anemonaes, and sea cucumbers can be kept with these sorts of tanks.
now add fish! the heartiest first, one or two or at themost three, for a large tank, at a time. always wait a couple weeks before adding more fish; and always test water when you go to buy a new critter.
20-25% water change once a month. siphon gravel/coral out to remove waste and extra food. test water once a month as well--right before scheduled waterchange.
good luck ^_^
saltwater tanks are *not* impossible, as long as you set them up properly and take your time. its a larger investment, but really well worth it in the end.