I see that a previous article gets lots of hits from people who want to put the falling snowflakes script on their Tumblr pages.
In order to put this script you need to go to your page and click "Customize". Then you will need need to click "Edit HTML", scroll down to the end of the code and before </body> paste this code:
Don't forget to save ;)
The script can be used also on Wordpress, Blogger or other CMS.
If you want to download the script or just to share your appreciation for it go to peters1.dk