How do I move my iphone backup to an external hard drive?

I tried following the instructions online. I moved the file "MobileSync" backup file to my external HDD but I cannot point the sync/backup to 'see' it.

I tried creating an alias but that did not work ...*

I tried the TERMINAL command: -s/Volumes/name-of-your-external-drive/ios-backup/~/Library/Application Support /MobileSync/Backup/name-of-your-backup-folder

Of course, I used my HDD name and the name of the backup folder (is terminal confused because my HDD has a dash in its name?)

I tried creating this path on my external drive but 'no such file or directory.'

I tried eliminating and leaving in the space after Application Support.

Is this even the right command??

*I also cannot see the LIBRARY folder my user name anymore? I did not toss it, is it hidden? Is it always hidden??