Since it appears that, in your dropdown, the text and value are the same, you could use the DOM to easily grab the selected text item and write it elsewhere.
You need to give any items you wish an
id='something', each something unique from other somethings on the page.
To get the value selected in the drop down:
Add an onchange="" event to the Dropdown
In the onchange event you'd get the currently chosen value:
<script type = 'text/javascript'>
function Handler_for_onchant() {
var picked = document.getElementById('your_select_control_ID').value;
// now update the textbox:
document.write.getElementById('your_textbox_control_ID').value = picked;
</script>
You should get proficient with DOM if you wish to do web development