So I posted this on the wrong one before haha, but basically I am trying to upload my own backgrounds. I want a 3 panel one which should be 1920 x 1136, and I am uploading a picture of that size but it comes up with a thing saying that my picture was only 292 x 173 but it was 1029 x 1136 exactly.
Maybe increasing the size of the picture a bit more than the current size should help.
And if you need any splashes, covers etc. for your story now or later, you can always come to this shop.