What to do in IT?

i feel like, and i have also heard a lot of people say that private textbooks have irrelevant stuff. So from where can I get the NCERT IT textbook, and how should I study it? Should I memorize stuff rn or in the 8 gap days? Is it doable in a week?

Also I have a shitty school so the textbook they prescribed may also be bad. What should I do?