GNU/Linux Lubuntu Installing Broadcom BCM4331 Driver Guide
Hi! The linked Tutorial shows you Step-by-Step How to Install Broadcom BCM4331 Wi-fi/Bluetooth Driver in Lubuntu GNU/Linux Desktop.
The Package Provides the Source Code for the wl Kernel Modules and makes use of the DKMS Build Utility to Install them for the Running Kernel.
GNU/Linux Lubuntu Broadcom BCM4331 Driver Installation Guide