Its there on the page already mentioned, http://linuxwireless.org/en/users/Drivers/b43
. I guess why you couldn't understand is because of this.
1. wget is commonly used download manager, so where ever you see wget -c XXXX , where XXX is a filename. Download it on windows.
2. files with .tar.gz extensions are compressed files, like zip. There are some windows programs available online which you can use to untar it, but in your case after mounting the windows partition on linux, untar it there on linux.
Whenever in doubt what command does, just do man XXXX, where XXXX is the command.