To load images from the location you currently have them stored use get_site_url() to generate a path:

$a = date('md').".jpg";
$a = get_site_url(null,'images/'.$a);
// var_dump($a);

Then use that information to create an img tag.

I would recommend loading the images from a theme folder, if this is part of a particular theme. If that is the case use get_stylesheet_directory_uri() instead. If this is part of a plugin, use plugins_url()