<?php

if (isset($_POST['submit']))
{
	$kop = mysql_real_escape_string($_POST['severity']);
}
else
{
	// Assuming you keep your html and php together
?>
	<form action="">
		severity: <input type="text" name="severity" />
		<input type="submit" name="submit" value="Submit" />
	</form>

<?
}
?>