Okie dokie, so you'll need to put it in the 
manage function. (Assuming you want it to appear while a user is managing an individual pet). 
You can do it like this:
Under the manage function you'll see this:
	PHP Code:
	
		
			
        $mysidia = Registry::get("mysidia");
        $aid = $this->getField("aid")->getValue();
        $name = $this->getField("name")->getValue();
        $image = $this->getField("image");
        
        $document = $this->document;        
        $document->setTitle("Managing {$name}");
        $document->add($image);
        $document->add(new Comment("<br><br>This page allows you to manage {$name}.  Click on an option below to change settings.<br>")); 
		
	
 Now remove the 
$document->add($image);. Go to the new Comment below that and replace the text within the " " with this:
	PHP Code:
	
		
			
<div style='background:{$adopt->background} no-repeat;vertical-align:bottom;text-align:center;'><img src='{$adopt->getImage()}'/></div><br><br>This page allows you to manage {$name}.  Click on an option below to change settings.<br> 
		
	
 I think that should work, though I haven't tested it because my manage function is heavily modified, so I had to find the original and edit it.