Step 1.
Go to here to select the model you want to edit or use

Step 2
Go to the Skin Textures section

Step 4
This is the Skin textures Section is it broken down in to five main sections
Diffuse = Main Textures
Decal = Overlays eg tattoos/scars
Specular = SSS textures will give you a wet/shine look
Gloss = will give you a dark/shadows and shine
Normal = Depth to the Textures

Step five
At this section you look through your textures to find the desired textures to apply and so on for each section.

I hope this helps if you need more help I'm here.
Crazy
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