I use this free image uploader -
https://imgbb.com/ - I have never made an account for it, it isn't necessary.
Upload your image and this is what you'll see - choose "BBCode full linked" and copy (you can highlight and do
control + C or they have a copy button that does the same thing):
When I come back to the forum and paste the code into the reply box, I delete the highlighted bits as seen in the screenshot.
You can leave them if you want, I just find them annoying:
