To use this add-on:

Simply install it to your site and add the block to a page. You will then have cool 3D snow on that page.

Alternately you can add the block to a Global Area, and you will then have snow on all your pages.

If you have problems:

If in any case this add-on brakes your site you simply go to (www.yoursite.com/index.php/dashboard/extend/install), and from here uninstall the add-on "C5DK Merry Christmas" add-on.

This add-on uses 2 global loaded scripts:

snow.js
ThreeCanvas.js 

Merru Christmas...