To Add a little to the above answers:
If you are wanting to commit a folder like the above
git add foldername
git commit -m "commit operation"
To add the folder you will need to be on the same level as, or above, the folder you are trying to add.
For example: App/Storage/Emails/email.php
If you are trying to add the "Storage" file but you have been working inside it on the email.php document you will not be able to add the "Storage" file unless you have 'changed directory' (cd ../) back up to the same level, or higher, as the Storage file itself