When preparing for any exam like NET the greatest hindrance is that I don't know much 11th, 12th basics like integration, etc. What do I do?

I'm currently in M.Sc. Physics final year and starting to prepare for CSIR NET. But I can't really move forward and always get stuck in the basics. I mean, if there's any new concept I learn it easily, but in problems, when you have to use 11th or 12th skills, I can't seem to be able to do that.