First, posting pictures of your code is nowhere near as good as posting your real code. We can't cut and paste mistakes from your pictures.
Also, once we go to reply mode, the pictures go away.
I can't figure out how to put ",2" character to get two decimals on Serial monitor.
It goes INSIDE the parentheses. It's an optional argument. It's also the default. Of course, it only applies to printing floats or doubles (which are really floats, too). Printing an int to two decimal places makes no sense.
On second image, I can't understand an error in my void setup
Your code is full of errors. Some time spent with the reference page would be much more beneficial than my pointing them all out.