Some of the activities in this course use Linux based Operating Systems such as Ubuntu or Kali. If you are not familiar with Linux, go through the tutorial at Basic Linux Commands . In order to practice the commands you will need a Linux machine. Linux Survival is an excellent source that provides hands on exercises on a Linux emulator. Complete the first three modules in Linux Survival.
You can also log in to Netlab and start the Ubuntu machine or you can use a virtual machine on a virtualization platform (such as VirtualBox or VMWare Player).