That's so strange that you can't download the file. I found it unusual this time that name, address, and other information was requested on a form, before the site would allow the pdf to be downloaded.
I've italisized what I copied from the pdf file.
Put your cap and letter in an envelope and mail it by December 31, 2008 to:
Save the Children, Knit One, Save One
c/o The Doe Fund
173 Cook Street
Brooklyn, NY 11206