Tools to create/edit Skin Texture for any 3D Human Model?

Hi,

I have downloaded a sample 3D human model, and trying to add skin texture for that 3D human model. I downloaded a sample skin texture (Pls refer below url for the sample skin texture), but it doesn't 100% fit into my 3D human model, so i tried to edit the skin texture using photoshop, but it doesn't give proper output(with the right resolution).
So,
1) What is the right 3d editor tool to create such skin texture image?
2) What is the right 3d editor tool to edit such existing skin texture image?

Sample skin texture url path:
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Thanks in advance.

Typically one uses photoshop (or equivalent) to modify photos for basic character textures. What do you mean by the output being the wrong resolution?