explain rating system please

i have searched site, but can't find an explaiation of chess.com ratings

i have just started and have a (unrated) after my name

Being unrated, you are under a provisional rating. You actually have a 1200 starting rating (not shown), however, your rating is unreliable and volitile because you haven't played enough games. The system used is the Glicko rating system. It is a bit complicated, but basically means that your rating change is based on the differences of ratings, whether you win/lose/draw, and how many games you have played within a certain time frame. The more games you have played, the more reliable your rating.

Thanks for answer. My question has been solved. I just recieved a rating after my second game & win