Blinking Eyes?

I would like to give someone Blinking eyes in a looping animation. When you double click on an abject to edit it and it takes you to its own timeline, I saw how to tell the image to go to a next frame in a how to video but I forgot to bookmark it and I have no idea how to find it again. Does anyone know what to call doing this and how to tell the the image to switch to its next frame?