you can write javascript function to pass the value as Query String.
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Untitled Page</title>
<script language="javascript">
function fnopenPage()
{
var val = document.getElementById('txtBoxId').value;
var url = 'Page2.aspx?value=' + val +'';
window.open(url,'_blank');
}
</script>
</head>
<body>
<form runat="server">
<input id="txtBoxId" type="text" />
<u>
<span id="id1" onclick="fnopenPage()">Click Here</span>
</u>
</form>
</body>
</html>
Please mark as answer if it solved your problem
with regards
Karthik Harve