If you’ve ever wanted to add explanations or help documentation directly to specific dashboard screen(s), here’s how.

In either a plugin, or your theme’s functions.php file, place this code:

Explanation

Lines 8-18: Enter your content for this tab. Full HTML allowed. (Watch out for single quotes, as these might break things)

Line 23: Change “Video Documentation” to whatever you want your tab named.

Lines 34 and 37: Choose whether to display on all screens (line 37) or just a specific page (line 34). See here for what the names of different admin screens are named: https://codex.wordpress.org/Administration_Menus#Using_add_submenu_page

Credit to this post for guidance:
http://wordpress.stackexchange.com/questions/124979/how-to-add-a-help-tab-to-all-admin-pages-including-plugin-pages