Adding an image to the home page
You can simply create a node, and put this node (eg. node/15) in the admin/config/system/site-information default frontpage field.

Otherwise you can also create a custom  page with hook_menu() like this:

$items[path] = array(
    'title callback' =&gt; 'page title',
    'page callback' =&gt; 'page_callback',
    'access callback' =&gt; 'access_callback',
    'type' =&gt; MENU_SUGGESTED_ITEM,
);


and in page_callback() you can return your  custom theme template/function.

Or simply use some contributed modules like "Empty Page", "Front Page", "Empty Front Page" and others..