I think that is the wrong place to begin.
One reason is that procfs is deep in the kernel, with lots of interfaces scattered over the kernel. An error there could just crash a system, without giving sufficient information for debugging.
If you are a C programmer already, it would be better to start with the kernel newbies list and performing the slightly simpler "cleanup" functions first (http://kernelnewbies.org/
). It will get you familiar with the kernel developers, style, and processes for better experience.