IIIIITHE1IIIII on 14 June 2015
To post an image saved on your computer you first need to upload it to a website. "imgur.com" is one of the most convenient sites for this purpose. (signing up is quick and easy)
Once the image is uploaded, right-click on the image and select "copy image location" or "copy image URL" or whatever it is called on your browser.
Using "Rich Text Reply", click the green "insert/edit image" button, paste the image location and then click "insert".
If the image is too big, highlight it, click "insert/edit image" again and try smaller dimensions.
It may seem like a hassle, but you only need to learn it once to be able to post images for a lifetime.
