Add a custom image background to shopify store

Store Design
1

I am trying to figure out how to add an image as the background of my entire shopify store. Ive seen a couple suggestions that I tried and did not work, ive seen some for just one specific page. I want it for the entire store.

ETA: I am using the studio theme

2

I think it’ll be best if you hire a developer(Shopify partner) for that

3

please share the store URL and the image that you want to share.