Shucks
Chess rating system

I've played one game with a greeter and now a second online game. My profile says unrated. Does it change automagically or do I have to do something to be "rated."

In playing my first game on Chess.com, I received a rating of 1200, before I played. Why, and how was that arrived at?
everyone has that. on chesscube you start of at 1500.
You start at 1500 on facebook chess too.
Black to move. Find winning combination.
I found first move, but made mistake later and in the end I lost this game. I'm not very happy about it as you may guess... My rating dropped to 1858.
1...Nhg5 looks good to me. I see no good defense for white: 2. hg5 Qh7+ 3. Nh2 Rh4 looks like it mates
That's how I played and lost game after 4. Qd6
1...Nhg5 2. hg5 that's the start of combination
2... Qh7+ is losing, there is much better possibility
as I wrote, it is wining combination
I play rating games with computer. 2 hours/40 moves, so it is plenty of time.
Anyway, computer needs 1 second only to move
I need much more time...
I have to go. Bye!
In playing my first game on Chess.com, I received a rating of 1200, before I played. Why, and how was that arrived at?
everyone has that. on chesscube you start of at 1500.