Hello and welcome!
The picture you showed above is definitely a reef tank. It has numerous species of coral. I'm still a 'rookie' but I have a few bits of advice and hopefully I can help you a little.
A 'reef tank' is a salt water aquarium with coral. The other salt water option is a 'Fish Only with Live Rock' also known as a FOWLR. When you set up the tank, aside from choosing equipment (filtration, lighting, heater, etc...) you'll want to decide if you'd like a reef tank or FOWLR. Knowing that will help you decide which fish would be appropriate in your system, it will also help you decide what sort of equipment you'll need.
Some fish are considered 'reef safe', which means that they won't harm your corals, and some fish aren't reef safe (they'll nip at your corals and eventually kill them). Another important thing to take into consideration is your lighting. Some coral require really strong lighting, while other types aren't photosynthetic and only need low to moderate lighting. It looks like the tank in the above picture probably has some really strong lighting (based on the type of coral that they have).
Once your equipment is set up, water/sand/live rock added, then you'll want to kick off the nitrogen cycle of your aquarium. Make sure you get a test kit and monitor your water as it goes through it's initial cycle. The water in your tank will continuously cycle. It's during the first cycle that you'll have 'spikes' in ammonia, nitrites, and nitrates. Only after your water parameters are safe and consistent should you add fish.
Before you add any fish to your 90 gallon DT (display tank), I highly suggest setting up a basic QT (quarantine tank). It's cheap and easy to set up a QT and it could potentially prevent fish illness/death, save you lots of $, and stress. Even if you if you trust the place where you get your fish, you just never know...
After your fish have spent time in the QT (the amount of time differs depending on who you ask) and the water parameters of your DT are safe than you can move them into your new tank. If you decide to have a reef tank, then after some time (that amount of time also differs depending on who you ask), then you can begin to slowly add coral. You'll want to QT your new coral just like you do for new fish.
There are a lot of threads on SWF.com with advice on how to set up a QT.
I hope I was able to provide some help. Please don't hesitate to ask any questions