How to download .dxf files

Use WinZIP (or equivalent) to unpack these files.
Use the File > Import menu command (most 3D programs have something like this) to import the files.
In some programs, you will need to scale down the objects (this can sometimes be done within the Import dialog box).
You can also view the ASCII contents of the files using any text editor.

About dxf files
dxf files, invented by AutoCAD, can be imported by many CAD and 3D graphics programs, including Ray Dream Studio 5, Caligari Truespace 4, Metacreations Bryce 3D and 4.0, Studio Pro 2.5.3, Amapi 4, Cinema 4DXL.