I use the GIMP it is similar to photoshop but it is free and much better name. :)
You can get away with a lot just by using the sites, image generator.
You can combine pics together nicely just by using PNG files. For example you can use this green arrow to make your own upvote pics very easily.
https://openclipart.org/image/2400px/svg_to_png/12139/pitr-green-arrows-set-1.png