How can I improve my Studio Theme's header and mega menu design?

I am using the Studio Theme and would like to make the header background and mega menu look better. Currently it is just a plain color, no design at all. I would like to add a background image to the header or maybe the mega menu. Just give it some flair. Can any one provide code that I can add and adjust to create a more visibly pleasing header/mega menu area? I know how to change code to get the look I want, just don’t know how to create the code. Also tell me where to add it in the edit CSS section. https://newdawnart.com/

@ddenby

Please share the screenshot of what you want or the Ref. shop url etc.

Thanks!

Maybe a menu that similar to the one shown in this image.

Background image: https://cdn.shopify.com/s/files/1/0795/3308/0877/files/New_Dawn_Art_Abstract_Art_Charlotte_NC3.jpg?v=1689375543

On the left hand side would be (in text)

SHOP BY (Header)

All Painting (link)
By Type
By Size

On the right hand side would be size collections with thumbnails. There are 12 so the thumbnails would need to be small.