Put img: before the URL
Upload an animated gif to a forum thread.
Save the URL for the image
Find the word you are looking to create a mem for
Select "try another mem" from the options that appear when you get the word wrong
Click the "Back arrow"; this immediately takes you to the "add a mem" option
Click on "add a mem"
Click on "Skip Search"
In the text box under the buttons "Image" and "Upload", paste in the url of the gifs location. At first, the url will appear in the window to the left.
Add " to the front of the URL with no spaces. You will see the active animation appear in the window on the left