Got to step 10 and totally lost as to what to do. It says...

Extract the zip file obtained from step 8 and change the working directory to the
folder that was created during the unzip process

So I've got Terminal open. I've got a folder on my desktop that has the zip file and in that folder I double clicked the zip folder and now have a folder called 22000 and within that many files and a sub-folder called files. 

I'm not tracking with with what I need to do to change the working directory and how that then works to create the ISO file. 

Anyone have more detailed instruction on what this step entails? For non-techie people, this really should be a YouTube video so I can see what the heck is actually being asked to do here. Sigh.