When viewing the PHP Info look for _SERVER["DOCUMENT_ROOT"]
Now after you create the .htaccess and .htpasswd files you upload the .htaccess to the /admincp directory and the .htpasswd to the level above public_html in a folder called .htpasswds (or create one if it does not exist).
*You must ensure though that the path in the .htaccess is correct and that it knows where to locate .htpasswd otherwise how does it know if your password is correct

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