A Quick and simple video on how to create a 10.13.6 USB memory stick installer on you Mac.
This link may help you with the terminal command:
How to edit a user on a Mac
A Quick video on how to edit a user on a Mac once it has been created.
How to reduce the size of a PDF using preview on a Mac
Here is a quick video on how to use preview on a mac in reducing a PDF to a size that would be manageable for any email client. Also show the option of using a downloadable filter to use in preview for different PDF size conversions.
https://discussions.apple.com/thread/4975061?tstart=0