History and Geography CDS

Could someone please help me? I am going to attempt the CDS exam for the first time and have never studied history or geography. I noticed that both subjects contribute significantly to the General Studies sections. Could you suggest where I should find lectures? I have access to the Parmar SSC 4.0 batch. Should I watch those, or would it be better to use one-shot videos for both subjects? I'm feeling very anxious about this. Please help!