In Apache web server you may an error "403 Forbidden"  when you open the websites on browser. You want to check in two ways,

Index file must be under the document root directory or set default file name to DirectoryIndex in httpd.conf and
should give correct permission to that file or directories.

DirectoryIndex: Its used to sets the file name for Apache will serve if a directory is requested

Find your apache installed path by whereis command,

# whereis httpd

httpd: /usr/sbin/httpd.worker /usr/sbin/httpd /usr/sbin/httpd.event /etc/httpd /usr/lib/httpd /usr/share/man/man8/httpd.8.gz

# vim /etc/httpd/conf/httpd.conf

DirectoryIndex  index.html index.htm index.php index.php5

Once you have updated these configuration restart apache server,
# /etc/init.d/httpd restart

Stopping httpd:                                [  OK  ]
Starting httpd:                                [  OK  ]