I have made many character mods over the years and now that true co-op is out I never figured out how to change my custom characters in the select menu/scroll wheel to be anything but blank! I have no idea where to begin since my mods are all gameplay not visual.

I'm not very good at art at all, but if I could even figure out how to do it would be great, then maybe I could use just symbols, like an in-game item sprite for example to corollate to each characters flavor. All I want is a single guide, video or not, that explains to me like im 5, then I'll be the happiest little boy in the basement c: !!

Any and all help would be great, I have seen some mods with this changed so I know it's possible and the information exists SOMEWHERE.

About my sitch: I have exactly 30 characters so if I only have one universal sheet to place all my sprites I may not have enough room, but if I could even do some that would be great. Because as of now, I have resorted to naming each character with a number THEN their actual name so I can easily remember and have a note beside me when I want to decide which character I get / roll a d20 :3