The main issue I have is that I want to make a pre-existing picture I made the background image for both the main page and for any articles on my wiki . I've seen on other wikis they have what look to be either JPGs or PNGs as the background for those pages, but I'm not sure what I'm doing wrong: theme designer on the admin dashboard did nothing, I tried setting it via uploading first as a picture and that didn't work, etc. I'll put the image I made below, I'm just not sure what to do.
Fandyllic wrote: Read Help:Theme Designer more closely. You need to make sure your image is a JPG, PNG, or GIF and is smaller than 300 KB. It looks like your image is way far over the file size limit at 1.13 MB.
Just shrunk file size and uploaded it, but now it's the background for everything but the main page. Re-read the Theme Designer and Background help, nothing seems particularly helpful.