Carl, yes...it is not easy to break into this strange world of linux audio programming. I'm a newbie myself...and while I have never used libsndfile directly, I will be doing that over the next two weeks. So I can share my own experiences with you.
I'm assuming you know C/C++ and coding with that on Linux(?). The libsndfile homepage is this (you've probably seen it already): http://www.mega-nerd.com/libsndfile/