Well, you’re in the Ion Blaster folder. If you look in the topic, you can see that there are pictures with the same names:
Whichever one you pick is the one that will replace your Ion Blaster. So if you like the look of, say, the “Retro Blaster” then you can pick that one, and then that design will replace the Ion Blaster in game.
Make sure you know what you’re doing before you mod, though - the readme should explain things. Hope this helps! 
All good, as long as it doesn’t become a habit, aha
In fact something pretty similar just popped up in the topic itself that I didn’t know, so it would be kind of hypocritical of me to complain, lol