The given PHP example helps you to add your own logo to WordPress dashboard. Add the following lines of code to your theme's function.php file.
Code Example:
<?php add_action('admin_head', 'my_custom_logo'); function my_custom_logo() { echo ' <style type="text/css"> #header-logo { background-image: url('.get_bloginfo("template_directory").'/images/your-logo.jpg) !important; } </style> '; } ?>