HTTP 403 Forbidden

I have upload all my files via Smart FTP, but when I go to my website I get this error message "HTTP 403 Forbidden" come up. Why is that?

Maybe you are using the wrong URL to access your files on the webserver? Or you have a .htaccess file in the folder you want to access? Please contact your web hosting provider for assistance. They have access to the server and can tell you what went wrong.

Regards,
Mat