Look at the top of the list of posts: you'll see some topmost, with the word 'sticky' beside them. Unlike regular comments, which constantly scroll off visibility, as new ones are made, sticky posts---and this is true across the web---are those intended to stay put and NOT move, so that people have them for reference. In every forum on Reef Central, there are different sticky posts, appropriate for the skill level and interests of users of that particular section.
It is a good idea for novices to read all the NTTH (aka newbies) stickies, then the Fish Disease stickies, and the Reef Discussion stickies. You can get some good information out of them. If you are thinking about fish, there is a section called Reef Fishes, which shares info on behavior and ease of keeping. There is a section for each type of corals, with their particular information. Don't be shy about visiting these various forums: they're open to everybody, and reading the stickies for each will give you a LOT of information. There is a DIY section for those who want to build. There are sections on various equipment.