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.