Hmm...your best bet is probably TIL. If you want to get into the lore, then you might as well read the lore and not necessarily anything "related" to it, and it would probably make sense to direct you to the FAQ thread first, then basically go from there.
But for the sake of ACTUALLY answering your question, I'll suggest maybe http://www.imperial-library.info/mwbooks/monomyth.shtml#Yokudan, http://www.imperial-library.info/mwbooks/anuad.shtml, and http://www.imperial-library.info/mwbooks/varietiesoffaith.shtml.
These are related and, in my opinion, a decent place to start, seeing as they deal with the creation of the world. Others may beg to differ, though.