CD = Civil Disorder = no one controlling the country = all units are automatically holding. If you don't enter any moves and don't open the game, the first turn it will become an NMR (No Moves Received), the second turn the country goes into CD. This means anyone else can take over. DON'T DO THIS. It's incredibly rude and destroys the game for the other six players, who will probably avoid you in the future.
Why isn't there an option to just quit a game? Why does it have to take a year? I'm not a developer here, but I'm guessing that if there was a "Leave" option, people would use it. And THIS IS BAD. It's very hard to find a sitter or someone to take over in a live game. We who play a lot of live games don't want people to just leave, we want people to join when they have the time. Make sure you have at least four hours to spare and a steady connection before joining a live game. Yes, stuff can come up. I understand that. But random stuff can't happen as often as some people resign. In my 200+ games, I've only been forced to resign twice.
If you know you have to leave and I'm online, PM me, I'll always sit in for your account. I try to save games whenever I can. Please don't abuse this just because you're bored with a game, but if there's some disaster, I can sit in.