Photoship: How do i recreate a similar image style with my maps? Help would be greatly apprecaited.

I'm a novice so if anyone could provide some general steps to help that would be greatly appreciated. 

1. I'm trying to recreate a map style similar to this screenshot from "Kings and Generals" Youtube. The red color that denotes the Roman Empire looks like it is embedded in the texture of the map. How do I recreate a similar style?

You can see in this map from Natural Earth I have started adding where the Carthegian empire (in green) would be, but it looks like i just painted over the top of the map. I used a gradient w/ multiply, but the stylistic differences are vast.  How do I get the colors to look similar to the one in the Roman Empire pic?

I greatly appreciate it help or direction.

Thank you. 

-David