Broadcom cards can be problematic. Have a look here -->
http://www.linuxquestions.org/hcl/showcat.php/cat/202 to see if yours is listed as working.
If not, run the commands '/sbin/lspci' ( without quotes ) and post the results.
Next run the command 'sbin/lsmod' ( without quotes ) and post the results.
From there we'll see if there are kernel modules loaded or not, and what hardware you have.
Once the modules are loaded, then you use ifconfig and iwconfig to configure the hardware. Some knowledge of your connection is required, things like are you running DHCP, your router make and configuration etc.
Edit: Did some searching, turned up this -->
http://www.linuxwireless.org/en/users/Drivers/b43
This looks like the module you need.