Making default replacement hair

[alinetjuh]

I tried several tutorials and looked all over the internet,
but nowhere I could find an explanation to make default replacements
(only texture, not the mesh) for hair
All of the tutorials I saw include an excisting default, but since I can't find any default for the hairtexture i want to change, it has no use
Does someone know where I can find a tutorial that explains how to make a defaukt without having to use an excisting one?