I have an Dell Inspiron 3520 that came pre-installed with windows 8. I installed Ubuntu 12.10 but wasn't able to locate/install the wireless driver and had to go back to windows 8. I'd rather have Ubuntu but I need my wifi.
First thing you need to do is download the driver. Do a google search for 'broadcom bcm43142 driver linux download deb' Download the appropriate .deb file. Then assuming you downloaded to ~/Downloads open a terminal and:
This will install DKMS first then the driver. You then need to reboot.
Hope this helps.