Main?Here is a very simple script alert.
<html>
<head>
<title>TITLE HERE</title>
<script language="javascript" type="text/javascript">
<!--
alert("INSERT YOUR TEXT HERE")
//-->
</script>
</head>
<body>
WEBSITE CONTENT
</body>
</html>
When a visitor accesses your page, they will receive a dialog box giving them whatever message you place in the "INSERT YOUR TEXT HERE" area. They can then press ok to enter your web page.