Agenda | Political Responsive WordPress theme

I have agenda | Bought Political Responsive WordPress theme. On the homepage is the newsletter registration a photo I want to change. Unfortunately I can not change, because this photo is on the server of http://agenda.chimpgroup.com.

I made a screeshot so you can see what I’m talking about.

How can I replace this image so that it is my server?

Here is agenda support contact here
http://chimpgroup.com/support/open.php

with your item purchase key

hope your issue will solved.