If your diving in head first then you need to start here:
http://usa.autodesk.com/adsk/servlet/index?id=472012&siteID=123112
Free or paid, you can get resources such as self learning materials, developer membership with that personal touch, and links to other 3rd party companies also burried in this type of programming.
Most of the stuff people learn at this level are self taught from these resources and this discussion group, as well as the afore mention book(plus others) and trial and error.
Welcome to the AutoCAD back door. Watch out for all the strange people you get to meet along the way (like me!!)
jvj
