Steps

1. Acquire an aquarium. This guide is for tanks less than 30 gallons. Decide on the location of the aquarium in your home. This place should have lots of circulation and have zero exposure to direct sunlight. Tanks of this size can frequently be placed on a sturdy piece of furniture. You can also purchase a pre-manufactured stand which may increase the warranty on an aquarium. Also be sure to get the items in the "Things You'll Need" section.
2. Fill the tank with water. Use RO water if available. City water works as long as you have a detoxifier. Otherwise get distilled water from the store. Be sure to leave about two to four inches at the top of the tank.
3. Add salt in small amount while checking with the hydrometer. Continue adding salt and stirring and checking salinity until the hydrometer reads 1.022 - 1.025. With a new hydrometer you will frequently get air bubbles stuck to the needle, these will seriously throw off a reading. Tap it up and down and left and right until they float off. Once you have an appropriate salinity take a break and let the water clear up. Check it again and proceed to the next step.
4. Put the entire unopened bag of sand into the water. Slice open one side of the bag and slide it out very gently. It is similar to the magician pulling out the table cloth, but a lot slower. If you do this properly the tank will hardly cloud at all. If you don't, you will have to wait longer for the water to clear so you can see through the aquarium. (You may use sand bought at the pet store or live sand bought from a local reef store)
5. Test the alkalinity and calcium levels. Read the directions for the test kit they vary in methods. Alkalinity reading should be 8-12 dKH. Calcium should be at 400-500 ppm. If either tests low, add an appropriate amount of alkalinity increaser or calcium increaser.
6. Place your rock in a way that is visually appealing to you. Keep in mind that you will need to clean the glass so leave enough room on any sides you will be cleaning, really important on the front pane. It is also advisable to stack the rock in an arch formation with many open holes and few touching regions.
7. Assemble the filter. Place the filter in a place where it will maximize the flow in the aquarium. The middle works better than the sides. If you are using two filters place them on opposite sides but not on the edges. Read the directions thoughly before you plug them in. Make sure the filters are running properly.
8. Put on the glass top, but leave the back plastic piece that comes with it off for now. Leaving this off allows a ventilation in the tank and keeps the temperature lower. Marine Tanks Need To Breathe.
9. Cycle the tank and wait around for 3 weeks to a month or two for ammonia, nitrite, and nitrate levels to zero out and the biological filters to establish.