Greasy Fork is available in English.
changes background on the web
// ==UserScript==
// @name Background changer
// @namespace lat.netne.net
// @version 0.1
// @include http://*
// @include https://*
// @include https://www.youtube.com/
// @include https://www.google.com/
// @description changes background on the web
// @author Warsoldier
// ==/UserScript==
window.onload = BG_change;
var isVisible = true;
function BG_change(){
if(isVisible){
document.body.style.backgroundImage = "url('http://www.hdwallpapery.com/static/images/cool-wallpapers-hd-8087-8418-hd-wallpapers_r11UrHZ.jpg')";//change the url address to your image you want around the web
}
}