I then merged all the layers in the first image (Layer – Merge All Layers), copied it, pasted it onto the enlarged canvas, positioned it immediately next to the original image, and adjusted the size. (If you made the canvas too big, just crop out the excess.)

Step 6
Finally, I added some text.

I chose to present this project more as a broad description of how I generated the result rather than as a detailed tutorial. The steps are not complicated and you can add a number of tweaks for a better outcome. For example, you might want to adjust the images so that the players are the same size. You might want to use colors other than white for the players.
— Thomas Boito