I need more help than I thought I did

Fresh off absolutely embarrassing myself in a summer analyst interview. I realised that while my degree prepared me for stuff like modelling DCF's and LBO's etc., I've somehow totally skipped out on the basics. As in, I can tell you what P/E and other multiples are, but I have absolutely no working knowledge when it comes to using them in real life. Could anyone please point me in the right direction of revising these fundamental topics? (And any other basics for that matter) Is there a WSO course?  

Thanks!