How to add an extra field below one of my product options

[court123]

I want to add an extra field below one of my product options

I know how to do HTML and CSS but when I move the code into the proper area of the listing_0.html template no changes show on my product page when I save the new file.
I am adding the code for extra field 8:
<!--START: extra_field_8-->
<tr>
<td colspan="3"><strong>[product_extrafield8]</strong></td>
</tr>
<tr>
<td class="item" colspan="3">[extra_field_8]</td>
</tr>
<!--END: extra_field_8-->

Into this section of code:

<!--START: file-format-->
[value]: [oprice]<br />
<input type="file" name="file[oname]" size="20" class="txtBoxStyle" />
<br />

<!--END: file-format-->

Is there something that is not refreshing? I have cleared cache and cookies etc

Please let me know - thanks in advance!