How To Make a Snowy Blog

First you go to Design(make sure your logged in).

Then go to Layout and click on Add A Gagect.

And then click on HTML/JavaScript (click on the + sign).

Next you make sure the title is blank.

Then type in this code in the "Content" box.

If this doesn't help much go to WitchHatBunny's blog she has more information about it.
http://animaljamflash.blogspot.com/2011/12/snowy-blog.html