joomla form

[yuuki]

In Joomla I want to create a form that posts values.

 

Of the fields I have a dropdown box, but when a checkbox for "other" is clicked I want a textbox to show.

 

How to I show/hide and post the select box's value or the textbox's value depending on whether the checkbox is checked (along with the other values on the form)? 

 

Thanks much for any help.