How does one go about making a gif, anyway?
I use GIMP, a free open-source image manipulation program.
Basically, in a gif, each frame is its own layer in the program. To make a gif from scratch, have a collection of images, make a new file and save it as a gif, and put each image in the file as its own layer. You can make additional changes by renaming the layers, like making frame 2 last 1000 milliseconds by renaming Frame 2 to "Frame 2(1000ms)" When saving it as a gif, select "Save as animation" and gimp walks you through additional options, such as whether the gif will transition between frames where each frame is displayed as its own entire image placed over the last, like a traditional paper flipbook animation, or if each frame will make cumulative changes to the base image, the very first layer in the file, as well as how long a time each unspecified frame will last.
So to make that gif of shook's dino, I saved both images shook made as png files on my hard drive, opened the first image in gimp, drag n dropped the second image into the same file and putting it in its own layer, then renamed the layers appropriately (Layer 1 to Background, Layer 2 to Frame 1, etc.) and then saving it as a gif. I then went back and made it better by duplicating both layers and relayering it so there's 6 frames instead of 2, and made the last frame last twice as long as the other frames (1000 milliseconds compared to 500 milliseconds) so the dino's movements looked more animated than a simple 2 frame animation.
I'm only familiar with making gifs with gimp, it may be different with different programs. The general principle of each layer being its own frame in the animation should stay true though. I learned by googling "how to make gifs in gimp" and experimenting.