I found that "practice makes perfect" with ye olde flight computer. The more you use it the more you will become comfortable with its use and will learn more about it.
A couple of quick exercises you can do at the dining table that helped me.
Try drawing up a fictional cross-country on your chart and working out a plog. Try doing two or three different plogs, perhaps with varying wind speeds/directions.
Try doing basic division/multiplication using the CRP-1.
You will get better the more you use it.
Many don't like the CRP-1 or its equivelants, will tell you its out of date piffle and to use an electronic computer instead. Fair enough that's their opinion. But for the PPL you will need to learn how to use it whether you like it or not. I detested Algebra and solving equations at school but I had to do it because it was part of the syllabus, now I see its relevance however and appreciate it. Once you get to know it and become comfortable with its use you will appreciate its usefulness, I still use mine all the time.
Smithy