How to Change the Logo?

[Faizann20]

global $page, $paged;

wp_title( '|', true, 'right' );

// Add the blog name.
bloginfo( 'name' );

// Add the blog description for the home/front page.
$site_description = get_bloginfo( 'description', 'display' );
if ( $site_description && ( is_home() || is_front_page() ) )
echo " | $site_description";

This is there, I need to replace it with a picture, how to do it?