How do you study in University?

I am in my first semester and well Its been a month and I have not studied properly for once like I used to in high school. Teachers provide slide for every lecture which are inadequate and all the books are in e form. So it's hard for me to actually study. Do you people just study from slides or use reference books? How do you manage your time? And how are you able to retain all the info for exams? Because I forget everything once I close my laptop. Any Tips?