Autodesk 123D is a CAD and 3D modelling software created by Autodesk. It is similar in scope to SketchUp and Fusion-360. However this is not as robust as the newer software's.
It has the basic 3D drawing and modelling capabilities with the ability to export your design to STL for 3D printing.
In addition to the installation software you will get tutorial PDF's on how to use the software.
