The possibly most important part of texturing is shading. You might recognize shading as the fading of colors on a map's terrain. How about you read
this?
Texturing consists of ^shading^, choosing the texture, and stretching the texture (not required, but sometimes desired).
I suggest you take a look at the default maps in a map editor. Which one are you using, by the way?
Don't forget the addition of scenery, the placement of pictures on the map. Read
this.