Onclick Changing Css Properties...

I think this board would be the best as it does hopefully end with an onclick element...
OK, I have a table, where I have ID'd the headers as such:

<table>
<col id="col1"><col id="col2"><col id="3">
<tr>
<td>Some Text</td>
<td>More Text</td>
<td>More Text</td>
<tr>
</table>

Now, when I click on the header row, I would like to hide a column, and when I click on an image, I'd like to restore it. Ideally, I would have a function like such:

function set_state(item, state)
{
if (state == 1)
{
item.css.visibility="collapsed";
}
elseif (state == 2)
{
item.css.visibility="hidden";
}
else
{
item.css.visibility="visible";
}}

However, I don't know how to pass the item along. Like telling it to hide col2, etc, etc.