you cannot upload....
you must -link- to a hosted picture....
so if you see something you wish to post, you need to get the url for that picture. (hint: it ends in .jpg usually)
you usually want to right click and copy the link
so for example...if i wanted to post the picture located at https://upload.wikimedia.org/wikipedia/commons/4/4a/Gregorio_Palamas_-_(Proprietà_Pietro_Chiaranz).jpg
I would click on the little picture icon above the open post window..(its right below the B (for bold)
that brings up the code for inserting an image
please note i had to remove brackets to get this to be visible......
img][/img
and in between the two IMG brackets you past the url for the picture.
img]https://upload.wikimedia.org/wikipedia/commons/4/4a/Gregorio_Palamas_-_(Proprietà_Pietro_Chiaranz).jpg[/img
like that....except don't remove parts of the brackets.....