How to add breadcrumbs to any WordPress theme

Try a breadcrumbs plugin. Breadcrumb NavXT is a popular option I believe.

An alternative solution of is just printing the name of the current page. Here’s what such a function might look like in its most basic form:

function wpse_87332_nav_identifier() {
    $page_name = get_the_title();
    echo "You are here: " . $page_name; 
}

Note that this will only work on single pages (posts, pages, media and custom post types etc.), and you’ll have to add some logic to display titles for archive pages.