I need a little help!!

I have a site where I have a dropdown with 4 values relating to various stores. What I need to do is after a store is selected a telephone number is displayed as a standard text field. I have added an attachment so that you can see what I am trying to achieve.


The form code is as follows

<div class="ccms_form_element cfdiv_select" id="phonenearest1_container_div" style=""><label>Nearest Store/label><select size="1" class="" title="" name="phonenearest">
<option value="">Please Select</option>
<option value="Lowestoft">Lowestoft</option>
<option value="Gt Yarmouth">Gt Yarmouth</option>
<option value="Norwich">Norwich</option>
<option value="Diss">Diss</option>
<div class="clear"></div><div id="error-message-phonenearest"></div></div><div class="ccms_form_element cfdiv_custom" id="input_id_2_container_div" style=""><label for="input_id_2">Telephone: </label><div class="clear"></div><div id="error-message-input_custom_2"></div></div><div class="ccms_form_element cfdiv_empty" id="empty_container_div" style=""><div class="clear"></div><div id="error-message-empty"></div></div>