Step 1: Get the image you want to pixel.
Step 2: Open it in GrafX2.
Step 3: Resize the image down to supersmall. Keep the aspect ratio the same.
Step 4: Make a new layer.
Step 5: Draw the pixels on that layer.
Step 6: Delete the supersmall image layer underneath it so that your image is just pixels.
Step 7: Resize the image back to the size it was before. Your small pixels are now big pixels, and they are all alone.
Step 8: Transparencize the image by right clicking on the LAYERS button and checking the Background box.
Step 9: Save it as a separate image. Also a gif because transparency.
YOU NOW HAVE YOUR BIG PIXELS.
Now for the nonpixels.
Step 10: Open the original image in GIMP.
Step 11: Open the big pixel image as a layer.
Step 12: That's it. You can mess with transparency, layer masks, blend modes, all that stuff.
Step 13: Repeat for every other pixel part you want. For my image in the stock photos topic, I used a separate images for the wings, the lasers, and the smoke and added them all into GIMP as separate layers.
Jet fuel can't make dank memes.