Materials Room. Go to the materials groups SkinHead and SkinTorso. These have a texture map plugged into the Diffuse_Color channel. First thing to try is to click on the color swatch in that channel and change it from white to a greenish off-white. In more general advice, tho; read the manual, especially read up on the section on Materials. There are a great many useful and potentially striking texture options within the editor and no simple forum post or even on-line tutorial can explore all of them.