@jusdoncarebear by Default your in your home-folder. so if you type
ls -lah
you can see the files and the Folders in your home Folder.
you can Change the Directory via
cd
(Change Directory + foldername or path to folder)
as the opt-folder is not in your home directory but in the root-directory you could Change to the root-directory via
cd /
if you type
ls -lah
again, you can see all the Folders in your root-directory (also opt).
to go to the opt Folder just type
cd opt
then you could type ls again to see the files and Directorys in there.
alternativly try to type
cd opt and hit the tab-button on your Keyboard multiple times. it will Show you the Folders in opt, so you can go quickly to a subfolder.
Hope this makes it more clearly