You would need a image editing program.
you find lots on
www.download.com
there should be so much there all the ones people mention are on that site.
Some cost money, some are shareware while some are free.
Then you'll need WC3 Viewer (download it in the tools section)
Use its tree list view to browse through its skin category in the mpq and if right click the skin file
extract and convert blp I recommend saving it as a 32bit .tga.
Start up your image editing program and find the extracted skin. Now start working on it. If I were you, I would get use to your image editing program and practice with it before doing skins. (try to understand the tools, its features etc) There are skinning tutorials on
www.samods.org/wcwarehouse (tutorials section)
A good way to start off on a skin is to:
- Zoom in at least 3 - 4 times.
- Your brush size should be lesser than 10 (depending on the skin your working on its details of course)
- Use the freehand selection tool
alot to get close to desired areas you want to skin.
If your done, save the changes as the .tga.
Use WC3 Viewer > Convert Files... > JPG/TGA/BMP > BLP and convert the skin to .blp If your promped on how to add a opaque alpha channel say yes.
Follow oz02's importing skin tutorial on how to import the skin.