Dynamic drop down list

Hello guys!..

I have this piece of code…

<div>

    <label class="fixedwidth">Number of Vehicles:</label>

    <select name="numberOfdrivers"><option>--</option><option value='1'>1</option><option value='2'>2</option><option value='3'>3</option><option value='4'>4</option><option value='5'>5</option></select>

    </div>

I want when a user select say 2 drivers to have a code which will generate the two other drop down list which I will be able to select the drivers from the database and then create the another form with which I will be adding the vehicle details of these drivers in a database…hope someone can help me…