Are you using apache as your web server?
if you are using apache then you need
make some modification to your httpd.conf
Here are the modifications
port (specify the port) eg
port 8080
or to have multiple web site with
different port you can use virtual host
here is the modification you will need to make to your httpd.conf
NameVirtualHost 157.x.x.x
<virtualHost 157.x.x.x>
DocumentRoot /usr/local/apache/htdoc
serverName
www.domain.com:8080
<virtualHost>
then stopped and started apache
Note
157.x.x.x will be your web server ip address
DocumentRoot will be were your web file are that html, htm or php files