For the inventory page, if you'd like an image there, add this in
view/inventoryview.php:
PHP Code:
$document->add(new Comment("<center><img src='' /></center>"));
right under this, which is lines 7-10:
PHP Code:
public function index(){
$mysidia = Registry::get("mysidia");
$document = $this->document;
$document->setTitle($mysidia->lang->inventory);
Then just place your image url in the quotes. Definitely don't use double quotes in the img tag, only singles.
Other pages should be similar, just add that same image line right under the document->setTitle lines. Just find all the -name-view.php files