1. Click the img button above the text field.
2. Paste the URL into the line on the box prompt. Modify if http is https, etc. so that it looks like the form in the image’s browser window.
3. Add a description in the next window.
4. Complete the post by typing the submit button.
5. Enjoy your embedded post.
Edit: the link on imgur isn’t the image’s url. On a phone, push and hold on the imgur image and select open in a new window. Then you get the link to the jog, png or gif image file that is needed in order to embed with the img button.