The Vault, as always, is your friend - as are the BioBoards.
What precisely are you looking for? If it's just a case of "How do I use the Toolset GUI?", then the old Bioware tutorial is still perfectly valid.
If it's a scripting question, you're better off looking through the good old reliable
NWN Lexicon, possibly the most comprehensive NWN scripting resource out there.
Again, though, precisely targeting what you should look at can only be determined if you tell us exactly what it is you want to learn.