Normally when you install quicklisp like this http://www.quicklisp.org/beta/#installation you should have this folder in your home directory.
/home/yourusername/quicklisp
and then you can find your installed libraries in
/home/yourusername/quicklisp/dists/quicklisp/software
and also you can add local asd file system in
/home/youusername/quicklisp/local-projects
maybe you install it when you were a superuser, to find this I think that you must use the shell command find to find the folder like in my fedora computer I did. here is the sample
sudo find / -name quicklisp
answer
Swipe your finger across the fingerprint reader
/home/anquegi/quicklisp
/home/anquegi/quicklisp/quicklisp
/home/anquegi/quicklisp/dists/quicklisp
/home/anquegi/.cache/common-lisp/abcl-1.3.1-fasl42-linux-x64/home/anquegi/quicklisp
/home/anquegi/.cache/common-lisp/abcl-1.3.1-fasl42-linux-x64/home/anquegi/quicklisp/quicklisp
/home/anquegi/.cache/common-lisp/sbcl-1.2.4-1.fc21-linux-x64/home/anquegi/quicklisp
/home/anquegi/.cache/common-lisp/sbcl-1.2.4-1.fc21-linux-x64/home/anquegi/quicklisp/quicklisp
/home/anquegi/.cache/common-lisp/sbcl-1.2.4-1.fc21-linux-x64/home/anquegi/quicklisp/dists/quicklisp
/home/anquegi/lib/lisp/quicklisp
find: ‘/run/user/1000/gvfs’: S’ha denegat el permís