What’s going on? Rules

I’m a new member and I can’t understand some of the rules. I signed up but there wasn’t any guide to explain the rules and what you can do. I just tapped to play and I thought I could choose to play with players on my level but the first time I played I saw a number 1200. I don’t know what this is. At the end of the game which I lost because I tried to figure out what it going on so I ended the game as fast as possible, I lost 170something points which I assumed is all the points I lost from blunders etc. What are these points? What happens when I lose them all? Where can I see my level and on which level I’m competing? And , in general where can I see my profile cause I can’t see it anywhere and see details about me , my points , my level and maybe a guide?

Ps : I just clicked on my profile and now I can see the points but 1) what are these points , there isn’t just one category, 2) where can I see my level and adjust it?, 3) where can I find a guide to explain how to manage the game?

Hi, welcome to the site. That is your rating. The purpose for it is to determine your level and pair you with players of similar strength. At first you will get a lot of points for a win and you will lose a lot of points for a loss, but after say 20 games rating will not fluctuate that much. 

Here is a more thorough explanation:

https://support.chess.com/article/210-how-do-ratings-work-on-chess-com