add items to a combobox

[Nina]

How do I add items to a combobox in a HTML doc with JavaScript?

the Combobox looks like this:

<SELECT id="select2" name="name2" style="HEIGHT: 22px; WIDTH: 142px">
<OPTION selected value="n/a"></OPTION>
</SELECT></P>


and here's the JavaScript function that I've got so far.
Depending on what item in another combobox the user clicked on, different items go into combobox2

function select1_onclick(val) 
{
	select2.clearAttributes;
	switch (val)
	{
		case "n/a": select2.clearAttributes; break;
		case "hs": 
                           
                           //add items to select2 

                           break;
		case "hm":

                           //add items to select2 

                           break;
		default:
                           break;
	}
}

Any suggestions?
Thanks in advance, Nina