Background not showing, Menus not working

Hi, i am using a theme called Reporter by Jinsona. I have designed a background for my website, but there is no space to upload it, also i have designed a header and still dont know how to upload it.

My menus are also not working, they were working on my former theme, but as soon as i changed to this one, they stopped showing!!…Help!!

My website is https://www.waohnaija.com