Hero image overlays the menu

Hi there,

I’m trying to work out why my siteorigin hero image covers my sticky header when it scrolls up.

As I’ve got it at the top of my contact screen it also covers any sub menu items that drop down when I hover.

I wonder if there’s a bit of code that might need changing?

I’m a pretty basic user of wordpress so step by step instructions might be very useful if possible please?

I’m loving this theme by the way, it really does exactly what I need…..almost..

Many thanks