Add school page

hi i need to add a school block and every school had their courses like

@safouane_don Could you give some more details of what you’re trying to do?
What do you mean by “school block”?

in fact i need to create a school page or block an each of them had their courses like i was looking for documentation for that i find nothing all wat i can do is creating couses and change the design

The page you have linked to is a marketing page. It is not part of Open edX but instead is rendered by a separate CMS (Content Management System). You could use Drupal, WordPress or some other CMS for these pages.

cause i find an organization part in the /admin but i cant show it in the front as organization

Organizations are a different concept. If you want a display like that page you can create a separate CMS site as I mentioned.