skills to document the netbsd kernel?

[Mayuresh Kathe <mayuresh%sdf.org@localhost>]

while i possess decent technical skills, i lack knowledge of
ansi-c which i believe would be a must to read the source of
the netbsd kernel and most of the userland.
my question is; what topics should i acquire command over to
understand the netbsd kernel source with the intent of
documenting it? i guess i should be well versed in operating
systems theory and practise, but what else?
thank you.