UTM in active campaign

I get to pass the utm through the Active Campaing form, how would I put it in this part of the code? Thank you

<div class=”_form_element _field40 _full_width ” >
<input type=”hidden” name=”field[40]” value=”” />
</div>
<div class=”_form_element _field42 _full_width ” >
<input type=”hidden” name=”field[42]” value=”” />
</div>
<div class=”_form_element _field43 _full_width ” >
<input type=”hidden” name=”field[43]” value=”” />
</div>

The page I need help with: [log in to see the link]