Image on Slider not Showing. help?

I love this theme! Congrats on something perfectly clean & simple..

am new to wordpress so I’m having a few issues..

1. How do I get my an image to post in the Thumbnail Slider?
Am able to create the post with an image once you click on it but it doesn’t show on the Home Page Slider.

2. How do I create additional Menus?
I have only been able to get 1 to work.

Many thanks!