Is there a reason why none of the pictures that I upload ever come out as wallpaper?

Hi, Hans! To put it simple, all you gotta do is go visit some site searching for a wallpaper, like let's say Wallpapercave, and then download the wallpaper to your device (PC, laptop, notebook, tablet, cell phone, or mobile phone, whatever). Just make sure that a file you're downloaded has a tag wallpaper in its name, or at least wp for short. Then upload that file to Fanpop and you won't get any trouble anymore. It's not so much a question of resolution, and the size in this case doesn't really matter, it's a question of your file name. Without a tag wallpaper, or wp in the file name, it would always come out as photo. Believe me, been there myself, only couple of months ago, when I was still a newbie on this site, much like you. I just uploaded a bunch of wallpapers to Charlie Puth fan club using the same trick of trade. You wanna try it yourself? It's so easy. You just need to be careful when you're downloading pictures. Any picture without a tag wallpaper, or wp for short, would go to photos by default. That's how this site works. It's not your fault, my friend, it's this Fanpop algorithm which makes it impossible for any newbie like you to upload wallpapers properly to any fan club on this site. Hope this helps. If not, let me know, okay? I'm only a mailbox away, my friend, and I'm always there for you. Even right now, when I'm drunk at some party on Saturday night with my friends. No, wait, it's already Sunday! Time sure flies, when you're having fun... And when you're drunk, like me, right now. So, what do you think of my answer? Not bad for someone who's been drinking all night.

Do they fit the wallpaper standards exactly, or are they just larger than the minimum stated? I know that they have to be a set of exact sizes, but I don't know what those sizes actually are. The same thing happens to me regularly - it's annoying.