What I'll be doing now is creating a mask for the uniform, since I want to darken it. What I like to do, is start out with this, duplicating my main texture a few times and making a group on the third one. I'll just be going over a few things of what I like to do while editing textures. This part is also completely different from what you may do, and this isn't meant to be followed word for word. If you know how to edit a picture, you can immediately skip this part and move onto the next one.
The main point of this part is getting your texture into your editing program and changing what you want.