I’m using imagebucket which is easy. But you have to use it from your laptop or PC (as another forum user helped me with) to pick the right picture size. Going from your phone is it pretty limited (when posting).
To answer the OP: No. You have to upload the image to Flickr or your own web site/blog etc. and then link here. You can't upload it directly to the GHQ forum.
Mark Severin
Owner, Scale Creep Miniatures
Author DeepFriedHappyMice.com
I "shared" my pictures of the old GHQ buildings I was reunited with on the wargames website (TWW) by starting a topic there. Then linked to my topic here.