The covers have to be uploaded as you did but it has to be checked by the admins first, the thing is that checking the covers take a lot and the quality control by them is that the cover has to be perfect.
So as lashek say, upload to mediafire, Dropbox, etc. And share the link in a thread, you can name it "Lemonkylie covers" or something like that, and the admins and other people can point what has to be fix. After that you can uploaded to the page and it's posible that it can make it to the page after been checked by admins again.
But first you have to share via mediafire, dropbox, box, etc.
