If you are using a Broadcom card in linux, the Broadcom site is going to be of no help. They don't produce linux drivers and won't let anyone else write one either.
However, you may be able to get it working through either ndiswrapper
. However linuxant charges for their driver. Both of these work on the same basic principle: They provide an interface for a Windows driver to work in Linux so you will need the Windows drivers for your card as well (the .inf and .sys files).
Unpacking files is pretty easy, for a .tar.gz file the command is tar zxvf filename.tar.gz and for a .tar.bz2 file the command is tar xjvf filename.tar.bz2.
Try doing a little searching around here for really basic questions, they have usually been answered multiptle times. In face I believe that there is a thread at the top of Linux-General that goes into great detail about installing programs.