I can't seem to mettre en ligne wallpapers. Could toi help me?

Ok, so first if this question was already asked just give me a link and rapporter the question (I do have to point out I searched before asking). If not:
Ok so I've been in fanpop for about a an and this whole an I haven't been able to post a fond d’écran ever!

I use Photoshop and when I save the fond d’écran I put it on maximum quality...Maybe I sound stupid but every time I mark the 1200x800 image as a fond d’écran it gets post over Photos.

Ok well I hope toi got what I said. Thanks for any help/advice toi can give me.