If there is a way to connect to the Internet, you can install the following packages in order to use wireless connections.
Open the Software Center and search&find&install these packages:
or you can install these packages with a terminal command(Short cut:Ctrl+Alt+T):
sudo apt-get install b43-fwcutter firmware-b43-installer
If your pc haven't a another internet connection, you can download driver packages from the following urls.
Please, be careful of packages architecture(The packages architecture you will choose must be same as your Ubuntu architecture.)
After this operation reboot your system and connect a wireless network.