To use the Wooden Floor in your scene you just need to go through this simple process which is as follows: a) Model the Floor of your interior Scene as a simple plane. b) Choose File -> Append -> Choose the proper blend File -> Choose Material, then "Wooden_Floor_Douglas_Fir_Herringbone_Pattern" Material. Assign this Material to your Floor. c) go to the UV-Image Editor and choose choose one of the image Textures. d) Now you need to UV Unwrap the Plane of your Floor. The most simple way is to switch to a view perpendicular to your Floor Plane, then choose "Project from View" for UV unwrapping. e) Tweak the Scale and location of your UV Map according to your needs along the Douglas Fir Image Texture. For further information of how to UV Map Meshes to Images, please check the Blender Wiki. f) If neccessary, tweak the settings of the Wooden Floor Material like shown in the image below. If there are any Questions left, please give me a coment and i will help you out as best as i can.