Question

How can we make notes and also how can we summarize answers or any text. And how to find key words of the given sentence.

Answer 1

It depends on our sense only.
There are no hard amd fast rules fpr paraphrasing and summarising but it only depends that which points seems to be important for you.
Select those important points and jot down on paper or you may simply underline them.

Answer 2

We can make notes by selecting those lines which you feel to be important,highlight them and write down on a page in your own simple words.Underline those words you feel complicated and find meaning of them separetly.