Domain name masking allows you to show one URL in the browser's address bar, while another website's content is actually loaded. For example, when somebody opens your website, you can have yourdomain.com shown in the browser's address bar while the actual site loaded will be yourotherdomain.com.
To achieve the above, an index.html file with the following code should be placed in the main folder foryourdomain.com:
/home/user/public_html/index.html
<html>
<head>
<title>Page Title</title>
<meta name="description" content="Description">
<meta name="keywords" content="Keyword1, Keyword2">
</head>
<frameset rows="100%,0" border="0">
<frame src="http://yourotherdomain.com" frameborder="0">
<frame frameborder="0">
</frameset>
</html>