cotir2005,
Was this the page where you downloaded the Mac Firefox version? -->
http://www.mozilla.com/en-US/firefox/all.html
You should be able to download it from there and then cut (or copy) and paste it to a flash drive and then move it over to your Mac desktop since it's a
*.dmg file type (aka Disk Image). I was able to transfer the download (all 17 MB of it) to a USB flash drive but I don't have a Mac to see what would happen next.
At what point did the process stop working for you?