<form action="https://www.google.com/search">
<input type="text" maxlength="100" size="50" name="q"><br><br>
<input name="as_sitesearch" id="as_sitesearch1" type="radio" value="IL TUO DOMINIO" checked=""> <label for="as_sitesearch1">Cerca nel sito</label>
</form>