WordPress: Add a help tab to an admin screen.

wp-functions-help-tab.php

<?php
/**
 * Add a help tab to the new/edit post screen.
 * Action: admin_head-post.php, admin_head-post-new.php
 */
function cmfy_add_gumbo_help_tab() {
	// Get the WP_Screen object
	$screen = get_current_screen();

	// Adjust / remove this conditional depending on which hook you're firing on
	if ( 'comm_cpt_gumbo_ingr' == $screen->post_type ) {
		$screen->add_help_tab( array(
			'id'		=> 'gumbo-info',
			'title'		=> __( 'Usage', 'cmfy' ),
			'content'	=>
				'<p>' . esc_html__( 'This post type will create a gumbo ingredient entry which is a small thumbnail with some hover information.', 'cmfy' ) . '</p>' .
				'<ul>' .
					'<li>' . __( '<strong>Title</strong> will show up when an icon is hovered over.', 'cmfy' ) . '</li>' .
					'<li>' . __( '<strong>Excerpt</strong> is currently not used on the front-end but is kept in place for a future addition.', 'cmfy' ) . '</li>' .
				'</ul>'
			) );

		$screen->set_help_sidebar( __( '<p><strong>For more information:</strong></p><p><a href="/gumbo">View Gumbo</a></p>', 'cmfy' ) );
	}
}
/**
 * Change actions depending on which screen you want the help tabs.
 * In this case, I want this help tab to fire on new / update post type.
 * I am restricing which post type with a conditional post type lookup inside of
 * the callback. For example, if you wanted to add a help tab to the
 * general options page, hook into 'admin_head-options-general.php'.
 */
add_action( 'admin_head-post.php', 'cmfy_add_gumbo_help_tab' );
add_action( 'admin_head-post-new.php', 'cmfy_add_gumbo_help_tab' );