Custom theme.Hooks not working? What I am missing?

Hello everybody.
I’m trying to make my first custom theme:
4 loops, 4 queries:
the first for the latest posts,
the second to display a contact form(Ninja Form),
the third to display one particular page,
the fourth to display one page that contains a Download Manager content.

Ninja forms doesn’t show (even if the editor of the browser, shows some kind of invisible ghost, with many contents, but no one appears on screen); as well, Download Manager.

I put wp_head before the </head> tag, wp_footer before </body> and wp_meta after I call dynamic_sidebar in my sidebar.php.

Moreover I tried to insert in my theme, the ninja forms function, as well as the short code version (and I did that for both the plugins).

This is the first site I ever made, and I will be ending the game, set and match without help.
Thank you in advance.
p.s. Just to give some more info: my site is one only page, that moves in horizontal thanks to Jquery, and every slice, shows the content of one loop, save the first, that shows a small animation and then disappear.
And I connect jquery and css via functions.php
p.p.s. Tell me which part of my code would be helpful yo display…