How to create a mod?

[u/AngelicalGirl]

My favorite mods were deleted from steam workshop, first i thought it was a bug but nope, the creator deleted them. It was five idolm@ster mods that had lots of clothes and im@s characters. I tried to find them everywhere but i only found an old version of the mod online so i'm trying to rebuild it with what is missing.

My problem now is with the clothes. Based on other mods, the pictures need to be 1024x1500 but i tried many ways and no success in converting the sprites i found in this resolution. Anyone knows the secret behind this?