You need to host them externally - with another service like photobucket, putfile (or about 100 others) and then link to the pic within your message using the
I chased free photo hosting sites for years. Seems what everyone was saying at one time was the best, would flake out a few months later. Finally settled on Photobucket and have been using it a couple of years now, and is the most recommended hosting site by administrators of other fora I visit.
Once you upload an image to Photobucket, they will give you the link to use in web fora that you can just copy and paste in your post here.