once you have installed the new texture... and have verified that it works well within the simulator....
you can change the design of the plane's tail (SEE THE PHOTO "00 tail.jpg")

-close the simulator
-go to the new texture folder (named "texture.N2627KRED")
-(SEE THE PHOTO "00 tail.jpg" inside the texture folder)
-inside it there is a file called "Tail_B.bmp"
-you can REPLACE it with another similar texture found in the "red black tail" and "red white tail" folders (or "full clean" folder)

don't OVERWRITE!!! just replace (for this you can use the "backup" folder... to store there the textures that you remove)