Good Lua book ( for Lua version 5.1 )
"Programming in Lua" from "Roberto Ierusalimschy"
Online sources ( Lua )
http://www.lua.org/manual/5.1/
http://lua.gts-stolberg.de/en
https://www.google.com
Online sources ( WoW )
http://wowpedia.org/
http://wowprogramming.com/
http://forums.wowace.com/index.php
Existing Add Ons to learn from the code ( be careful with this because there are enough AddOns out there that use bad code :P )
http://www.wowinterface.com/
http://www.curse.com/addons/wow
Other things
Start with a small testproject and play with things.
Dont throw keyboards they are Hardware no Throwware.
