First, follow the movement of the rotating pink dot:
Next, stare at the + sign in the center of the image.
Finally, concentrate for at least one minute on that same + sign.
Most people will see only a pink dot in Step 1. In Step 2, most will see the moving dot turn green. And in Step 3, after a short period of time, many people will see the pink dots slowly disappear. Some will also see only a green rotating dot.