You use the “cd” command to change the working directory when you are in the shell that’s open in the Terminal window. A web search for “unix change working directory” will give you more information on thie “cd” command and how to use it  

Opening the Terminal places you into a shell (that’s the equivalent of the Windows command prompt or Powershell) whose working directory is your account’s home folder. Your Desktop is a sub folder of your account’s home folder, (In Unix-like operating systems, folder and directory are synonymous). 

Let’s take an example. If you have a folder called “22000-something” on your Desktop, the following commands will change your working directory in the shell to this folder. :

cd Desktop
cd 22000-something

Or, the following single command will do the same thing starting in the same place

cd Desktop/22000-something

Videos are nice, but nothing takes the place of a well written manual. It’s easy to go back in a manual and use it as a reference. It’s not nowhere as easy to do that with a video - not unless you are taking copious notes as the video is playing.