I'm pretty new here too, which was/is pretty overwhelming, since the simulation has been running for what? Like 8 years? And there are some pretty hard-core established players.
There are lots of help documents around, but my general advice is to spend a little time building your nation up a bit, observing and reading to get the basic flow of how things work, and what kind of approach you want to take.
Every nation chooses a different balance between game-play (the simulator itself, with the national issues and world assembly votes) and role-play (which basically happens with in-character discussions in the on-site and off-site forums).
In my humble opinion, the game-play mechanics are pretty basic, with the richness of the community coming out in the role-play - which you can take as far as you want to. Some nations have amazingly detailed histories, maps and whatnot.
Welcome, and good luck!