common lips libary prolbem

So I used Quicklisp to download the ZPNG (http://www.xach.com/lisp/zpng/) library:

(ql:quickload "zpng")

and it downloads everything successfully and shit.  But when I try to make-instance a 'png it says

*** - FIND-CLASS: PNG does not name a class

Halp!

lisp
There's your problem!

>>1
Did you import the package's symbols into the current one? Or if you don't want to do that, refer to the right symbol in the right package (use package-name:symbol-name)

>>3
ah, didn't know I needed to import stuff.  got it now, thanks.