a simple demo will look like this
<html>
<head><title>Test URL</title></head>
<body>
<form action="search.php" method="get">
<input type="textbox" name="q" value="" /><br />
<select name="res">
<option value="10">10</option>
<option value="20">20</option>
<option value="30">30</option>
</select><br /><br />
<input class="submit" type="submit" value="Search" />
</form>
</body>
</html>
it will pass two strings like this
search.php?q=dd&res=10