If you don’t know how to edit an object, please read this first; community.secondlife.com
NOTE! Make sure you always use “Select face” in the edit mode when modifying a surface. If not – your entire building will be modified.
Right click the surface you want to modify and get into edit mode – Then click “Select face. Click the TEXTURE tab. All surfaces of our buildings have several layers. One for texture and colors and one for shadows / ambient occlusion. Left click the surface you want to modify until you see the texture you want to change appears in the little texture window. (We recommend not changing the shadow / ambient occlusion texture). Locate the texture you want to use in your inventory and drop it into the texture window. Make your changes and exit EDIT mode.