The 403 Forbidden error is typically a server related directory/file permissions. Contact your server admin or tech to look into this further. The web server error log may have additional information regarding the directory or file. This is a server related issue and because each server is different, the server admin or tech will need to resolve this at the server level.
Common cause of 403 error:
The directory or file may indeed not be accessible by intention, not an error but how the server is configured.
The directory or file may have the permission set incorrectly, causing the directory or file to be inaccessible on the browser. The sever admin should be able to provide the needed permission or inform you of the permission level needed for a directory or file.
If the 403 is on a directory, an index file (index.php, index.html, index.htm) may be missing. The directory index file is typically loaded by default and if that file is missing a 403 message may appear. Contact your web server admin to enable DirectoryIndex directive or simply place an index.php, index.html or index.htm file in the directory.