Open application > views > user_templates
Open links.php
On Line 83 add your Banner Code after </span></a>
On Line 85 add your Banner Code after </span></button>
Using a rotator code will help you run different banners and not have the same ad under all shortlinks.
Rotator code:
PHP:
<?php
$ads250 = array(
'CODE FOR THE AD1',
'CODE FOR THE AD2',
'CODE FOR THE AD3',
'CODE FOR THE AD4'
);
shuffle($ads250);
echo'
<div>
'.$ads250[0].'
</div>
';
?>