Wifi drivers wont function

I've been trying to get my WiFi drivers on my laptop working for a week or so now and every video and thread has not helped me out. I know I need to use sudo apt-get install b43-fwcutter but whenever I type it into terminal, I get:

Reading package lists... done 
Building dependency tree
Reading state information... Done 
E: Unable to locate package b43-fwcutter
A suggestion was to put lspci -vvnn | grep 14e4 in terminal:

09:Ethernet controller [0200]: Broadcom Corporation NetXtreme BCM5755M Giga bit Ethernet Pci Express [14e4:1673] (rev 02)
0c:00.0 Network controller [0280]: Broadcom Corporation Bcm4311 802.11b/g WLAN [14e4:4311](rev01) 
sudo apt-get install linux-firmware-nonfree:

Reading package lists... done
Building dependency tree
Reading state information... Done
E: Unable to locate package linux-firmware-nonfree

Your wireless card requires proprietary firmware to work. To install it without a working internet connection, download this file to your desktop. https://dl.dropboxusercontent.com/u/58267392/b43.zip Right-click it and select 'Extract Here.' Now open the terminal and do:

sudo mkdir /lib/firmware/b43
sudo cp Desktop/b43/*  /lib/firmware/b43
sudo modprobe -r b43 && sudo modprobe b43

Your wireless should now be working. I suggest, once this is done, you ask a new question to get your ethernet going.