I have updated to Ubuntu 17.10. Now I want to create a bootable USB stick to use on other machines or to install 17.10 on a new machine. Start up Disk Creator recognizes my USB Drive, but is looking for a CD/DVD containing a source file. I assume an ISO file. I cannot change the source location and even if could, I have no idea where to find the 17.10 ISO on my hard drive.

I found sample code to create the USB using the terminal but I can not get that to work either, I keep getting a message saying the add command can not be found!

Must I be signed into the root directory to use the necessary commands and if so how do I do that?