Copyright and Terms of use

Hello, I am designing a course (a paid course not free) about computer programming in Python programming language. I know Python and I can code with it, but sometimes I need to refresh my knowledge by looking at some websites that teach programs like w3schools.com / geeksforgeeks.org and more. Now the problem is that these websites are copyrighted and they don't allow anyone to copy from there materials. What I am doing is just looking at the basics of the programming language which is open source and free to use even for commercial purposes. Also, I don't copy directly from the websites. I do refresh my knowledge and I then type in my own style. Is that considered reform of their content? I will give an example: https://www.w3schools.com/python/python_datatypes.asp This link has a tutorial from w3schools.com and anyone is free to learn from them for free unless they are not using the materials for commercial purposes. The link contains some basic information about the python programming language (which is free), and this info is found on any other website (maybe in another style). I would just read the content from the link and I will type in my own way. The question: Is that illegal? or considered a copy or reforming? I think I have a bad understanding of what the forbidden copy actually is. sorry for not being brief. I hope I get a positive answer from you. Regards.