If you have a control panel, it should do this for you.
Below is an example of two functional vhosts for the domains domain1.com and site2.com.
HTML Code:
NameVirtualHost 123.123.123.123:80
<VirtualHost 123.123.123.123:80>
ServerName domain1.com
ServerAlias [url]www.domain1.com[/url]
ServerAlias ftp.domain1.com
DocumentRoot /home/domain1/public_html
</VirtualHost>
<VirtualHost 123.123.123.123:80>
ServerName site2.com
ServerAlias [url]www.site2.com[/url]
ServerAlias ftp.site2.com
DocumentRoot /home/site2/public_html
</VirtualHost>
Sorry it says that is HTML code, I had to wrap it in an HTML container on this forum to get it to show right. It goes in your httpd.conf. Of course you just need to change the IP, DocumentRoots and domains to match your needs.