Joe is right. You need to understand the basics of a saltwater aquarium. We have a few FAQ pages on this forum, 101 tips to starting and maintaining a saltwater aquarium would be a pretty good place to start.
Links:
https://forums.saltwaterfish.com/t/301033/101-tips-to-beginning-and-maintaining-a-saltwater-aquarium
https://forums.saltwaterfish.com/t/386044/let-s-talk-about-cycling
Welcome to the boards, hope you enjoy your stay.
Oh, also, you can start by reading the Conscientious Marine Aquarist, and a couple of other books on the subject. You also need to buy a couple of books that are "Guide to Marine Fishes" and "Guide to Marine Invertebrates."
Those books should get you pretty well started. It's not as simple as "add salt, fish, and snails." It's a very complicated process and with your aquarium being so small, even doubly so. Just a warning!
I also agree with Joe, You must first know how a SW tank works by doing research. After you have that if you have question then ask them. There are 2 really important things in this hobby. #1 is patience and #2 is to research, research, and research.....