Delete the Document path completely, there should not be anything there.
There is no log in name on the computer, when I go through your explanation below it only shows Everyone as an option.
You can't not have a username, it isn't possible.
Assuming you have a password for your account, use it, if you don't have a password, or don't know it, you have to create a user on the PC and give it a password, then add it to the share by clicking Add in the above screenshot in the folder sharing.
