Hello and welcome. I've only been a member for a couple of years, and I, too, found it confusing, but after a while I got better at it, although I've never figured out how to post pictures. I'm old and computers just aren't as obvious to me as they are to younger people. The EE section referred to is "Equipment Exchange", and I'm not sure you have to "prove" anything, but you do have to request access through one of the monitors. I've bought a few guns through EE and have always had a good experience. I have no idea how they make the decisions to let people use it, but when I applied it took only a couple of days for someone to let me know I could use it. I've found the whole site pretty good. Like all the other gun sales/exchange sites, you have to use honesty and common sense about what you put down for condition and price if you're selling, and ask the right questions if you're buying.
I've found the forums are useful and enjoyable. There's a lot of general gun information. They're really handy if you have problems that need an answer from someone with specific experience. There are a lot of opinions, some better than others.