Board Thread:Support Requests - Designing Your Wiki/@comment-39286675-20200421013238/@comment-44807868-20200421043958

To be more specific, you'll have to use following on MediaWiki:Wikia.css on the wiki you want it on:  Replace   with URL of the image; e.g..

The two instances of  overlay the background image with a certain color; whitish in this case. You'll have to replace it with a semi-transparent RGBA color in case you need an overlay of different color.

If it's confusing to you, just let me know of what changes you need for both aspects: the image and color you need for your purpose. :)