What is the procedure for creating a texture pack ? (not tiles)

[Tchernobill]

Using Tiled from Project Zomboid Modding Tool, I am not able to create a pack from pictures (not tiles)

I choose a directory with my png's and untick as those are not tiles but it creates no pack.

 

Using, Project Zomboid Pack Manager, I do not know how to edit the pictures in a pack (I only changed the picture names with an hexa editor, but I want to change sizes and picture numbers)

using Soulficher Farming Time pack as an exemple.

So how should I edit the meta data ?

 

Regards,