Math HLAA calculus guidance!

I'm a DP2 student, and I'm struggling to catch up with work in math class. I have a weak foundation in higher-level math. I have a test on the whole calculus topic in around 2 weeks. Any tips on how to study for maths for someone who literally doesn't know whats going on? Any materials or websites would be amazing help! Or if anyone has similar experience, please tell me!