Okay, i can get to change the background at index.css of the vertex theme, but that only changes one background, when i try to change the background of all the boards/home page, i just can't.. Can't find where is the code, have tried different parts and nothing, just get to change small blocks and not all as a whole site.

Also, if i use an image as background it doesn't fill the heigh of site, how can i do that without creating a huge image?