>>1
Disregard Land of Lisp. That book is crap. Pick up On Lisp, ANSI Common Lisp, and Paradigms of Artificial Intelligence Programming (PAIP). I assume you have downloaded a suitable Lisp (
Scheme? LOL!), but if you have not, download SBCL+Slime+Emacs. If you don't like emacs, select something from here:
http://www.cliki.net/development
If you want to just start hacking away, you can. Pick up a copy of the hyperspec and churn out some code. It'll probably be shitty, but you'll learn something at least.
Happy hacking.