Need help!

I don't know what to study for the entrance exam, and it's my first time going serious about reviewing and studying. So I don't know where to get the information (the definition and the instructions of the topic) or, what's the right review technique, or what to review (cause I don't even know a lot of topics)

There are a lot of sub topics like algebra, calculus etc. on math and chemistry, physics and etc on science.