Good fish, bad tank size.
10 gallon is not really a good fish to start with fish, its basically for eye candy, corals. 20g long would be a much better choice for keeping fish. Relatively easy also.
Dry Rock, there are a few hitchhickers on Live Rock that people want to stay away from, so they opt for using Dry Rock, or Dead Rock. Macro Rock is a good place to start looking for that. Either way you go you will need a minimum of 1lb per gallon.
Replacement filter media like filter floss and activated carbon (if you get a filter)
Multiple Powerheads (2 or 3) 10x your water volume for just a Fish Only With Live Rock, and at least 20x your water volume for a Reef Tank. So lets say your going reef, and you have a 100g tank, you would need flow in that tank at minimum of 2000gph, or 2 1000gph powerheads.
Protein Skimmer, rated at 2 times your water volume
Saltwater Test Kits.
Reef Test Kit. Test for Ammonia, Nitrites, Nitrates, PH, Phosphates, Calcium, ALK and Magnesium.
Saltwater fish food. Mysis Shrimp, Squid, Cyclopease, Algae Sheets, Romaine Lettuce . Flake food is not really a good food to feed your marine fish.
Aquarium vacuum. This one is iffy. Most don't use one, if you have enough flow in the tank you won’t need one
Rubber kitchen gloves
Fish net
Two, clean, never used before, 5-gallon buckets
Aquarium thermometer, digital being the best.
Brush with plastic bristles (old tooth brush) - needed for cleaning the live rock if you don't get Fully Cured Live Rock.
Power Strip, possibly GFCI outlets by the tank.
Optional but definitely recommend getting a Reverse Osmosis or RO/Deionization filter for the make-up water, and a barrel for storing the water.
Possibly a Quarantine Tank for your new fish. They sit in here for a few weeks to kill off parasites and bacteria, to keep it from getting in your main tank
Heater rated for your size tank.
Saltwater Mix. Marine
SaltSaltwater Hydrometer or even better a Refractometer, which is more accurate
Aquarium filter (not absolutely necessary if running with adequate amounts of live rock, but nice to have if you need to use a mechanical filter or activated carbon, etc.)Aquarium substrate such as live sand or crushed cora. Some go bare Bottom, others choose the 2-3" bottom, others, more advanced will try the Deep Sand Bed, which is over 6" deep.