Autodesk Inventor: How To Import STL Files

My goal is to learn how to design in 3D with software like Blender, but I am getting into the swing of 3D printing by learning the basics of Autodesk Inventor. A lot of people share their designs on Thingiverse, where you can download the designs and examine them. Autodesk Inventor can import .STL files, but you it doesn't appear you can do anything with them, let alone modify them... but there is a plugin.