U can use backgrounds for a lot of things..
If you use backgrounds as wallpaper for your pc, tablet or mobile phone than just take a normal background or a background in merry christmas You can also use backgrounds for in your powerpoint or your prezi to give your own twist to it. Or get them to use it on your website, but always make sure you ask the owner for permission if you use it for something like that. For personal use the backgrounds are free, but if you use them for anything else just ask the owner first. You can always use the backgrounds to get some inspiration. There is a huge range of backgrounds so for everybody there is something you like! My favourite backgrounds are designed backgrounds with a lot of colors!