Hi Eye To Eye,
Please go into Terminal (launch it from the LaunchPad tool), and then type in Terminal, click to run...
Once there, just type in the command (cd) and then ENTER, to take you into your home directory
From there you can do (pwd) and then ENTER to show your directory location, it should be something like (/Users/Heider), if you are not there, then try to go manually into your Users directory by doing (cd /Users) and then list them up by doing (ls -ltra) and then Enter, you should you user there (example: MyUserName). If you see it, then goto into it's directory by doing (cd MyUserName) and then Enter.
Now, from that location, you should be able to (cd) into the location by doing:
cd "Library/Application Support/Dock"
(notice there is no ~/ in the above (cd) command.
If you after that, you still can't find it, then your system might have some corruption in the file-system, even though the solution can be easy by just creating the folder there manually by doing (mkdir Dock), however, I recommend doing a disk-health-check before creating any items on the filesystem. This way any lost-chains would be salvaged and you won't risk your HD by causing more damage.
I hope this helps.
Kind Regards
Heider Sati