No problem! Greasemonkey is an add-on for firefox that lets people customize websites in various ways and borrow other people's customizations. So to install daluci's scripts, first you would have to install Greasemonkey (link above), then restart firefox, and then you should see an "install" button on the top right-hand corner of daluci's userscript page. After it's installed, it should work automatically; if not, there are greasemonkey options available in tools -> greasemonkey -> manage user scripts.

There are a lot of other useful scripts for greasemonkey at userscripts.org; for example, I use one that marks comments since my last page refresh as new on dw and lj.