First of all don't change filename because the filename of each bitmap has a sharp meaning.
Filename is in the following format: XYZ.bmp, where "X" is an ordinal number (0..7), "Y" can be "L" or "S" and "Z" can be "N", "H" or "D" if the bitmap represents the normal, hot or disabled state of the related button.
Example:
0ld.bmp is the large/disabled bitmap for the first button.
Use a graphic program to edit templates, then save them in a folder labeled with the name you want to give to your skin (example: "MySkin"); finally test skin in ZG Toolbar Skin Tester program and click "Build skin package" to make the "MySkin.ztk" file, which will be used by ZipGenius.
Make icons with 24bit color depth only, no alpha channel.
Use always fuchsia color (R 255, G 0, B 255) as icon background.
