can just paste the pic into the URL box. usually how I do it. general crowd complains about no thumbnail/expand. try anything and see what happens. my philosophy. (i'm usually surprised when I don't need spellcheck for big words) edit/rinse/repeat nobody notices.
it's a thing with the post form. believe me it was like that when I got here. I'm not real sure what the standard upload procedure is. tried many. here is the thumbnail list view. click thumbnail expand to large picture or the URL to off-site address. see pic