You should be able to go to the website where you registered "www.domain.com" and have it forwarded to the website you requested. If you have access to the server "www.domain.com" is pointing to, and for some reason cannot change where "www.domain.com" is sent to, a quick fix would be the HTML code below as your index.html.
Code:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Your Page Title</title>
<meta http-equiv="REFRESH" content="0;url=http://www.the-domain-you-want-to-redirect-to.com"></HEAD>
<BODY>
Optional page text here.
</BODY>
</HTML>