Hello, and welcome to the forum! There are way more experienced people on this forum than me and I'm sure they will chime in as well.
The main source of your filtration for a saltwater aquarium comes from your live rock. A good skimmer and plenty of live rock will serve you well. You will want to stay away from most freshwater type filters such as hang on the back or canister filters because these cause poor water quality in a saltwater aquarium.
Your source of water is also very important in a marine aquarium. Unlike with freshwater where tap water works fine, you will want to use ro/di water either from your LFS or through your own ro/di system. This can help you avoid major headaches with algae in the future. There are just too many unknown things in tap water that can spell disaster for your tank.
As far as fish go there are plenty of great fish out there that are pretty easy to care for and hardy. Clownfish are always a favorite in the hobby and my own personal favorite is the Royal Gramma. Just be sure to research any potential fish and ask questions about them if you have them. Remember not to add fish too quickly when it comes time. Only add about 1 fish a month unless it is a pair like 2 clowns. Also only keep about 1 fish for every 10 gallons of water. This is a good rule of thumb to avoid over stocking.
I look forward to seeing your tank progress!