Sorry you are having such a rough go with trying to show us your work.
I have a Mac and use Firefox and haven't experienced the problem with the Uploader that so many others have complained about. I'm not sure if it is the version of Firefox you may be using or something else????
You might try using the Attachment button below the window if the Uploader doesn't work. See if you can show us your work that way.
BTW, I've moved your thread from the Gallery which is only for showing finished paintings to Palette Talk which is for more general kinds of discussions.