Archive Drop Down (Month) code advise required

Hi there,

I found the code to get Archive’s in a drop down box by Month:

<select name=”archive-dropdown” onChange=’document.location.href=this.options[this.selectedIndex].value;’>
<option value=””><?php echo attribute_escape(__(‘Select Month’)); ?></option>
<?php wp_get_archives(‘type=monthly&format=option&show_post_count=1’); ?> </select>

I have tried a number of different things to get this code working through a “Submit” button rather than directly within the drop down box.

Does anyone have idea how to code this? Please feel free to see the site I am trying to get it work on:

https://www.exlmtraining.com/index.php/news