You need to learn more about HTML (check out HTML Help which is a great page about HTML tags).

Looking at your HTML it is clear that your form has an action (<form .. action=".." ..>). That action specifies what web page WWW::Mechanize should fetch when you submit the form.

Now looking at your image (<input type="image"...) it is clear that this image is not designed to actually perform any function by itself. It is likely that a javascript function elsewhere has tied itself to this image to make it clickable. Whatever that may be, the important information is already encoded in the form (the action as I mentioned earlier).

So just try this code instead while paying particular attention to the <form ...> tag:

  use WWW::Mechanize;
  use strict;

  my $agent = WWW::Mechanize->new();
  $agent->get('http://address');
  $agent->form_name('form1');
  $agent->field('request', 'test');
  $agent->submit(); # will go to the form's action URL
  print( $agent->response->content() );
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