changing values in a table column

changing values in a table column

I need to write to table cells in a given column. To illustrate:

<table id="tableName">
<tr>
     <td id="col1">some value</td>
     <td id="col2">some value</td>
</tr>
<tr>
     <td id="col1">some value</td>
     <td id="col2">some value</td>
</tr>
</table>


I'd like to be able to change values in one column or the other. Can someone provide me with the jQuery conventions for iterating through rows and writing to table elements, or otherwise point to a good source of information? I've looked around and so far haven't come up with much.

Thanks