Its really easy, you first choose the gif you wish to edit.

Upload that to a video editor like CapCut.

Then use the overlay tool and add your original image on top of that.

NOTE: Your image should be in GIF format.

Save the video file.

After that simply go to ezgif.com

Upload Video to convert to GIF.

BOOM, you got yourself a GIF.

Hope this helps brother :)