Well, the easiest way to do it is to just get a simple key duplicator, chuck an existing key for the car in one side, a blank in the other side, and copy the existing key. Certain high security keys require more elaborate and expensive machines.
Getting into transponders is a fairly large financial investment in equipment.
As for making keys for a car if you don't have an original key to start with, that gets into areas that would be covered in our advanced forum. Due to the potential of abuse of that kind of knowledge it's not something we go into in the regular forums.
Here is the information on accessing the advanced forums.
viewtopic.php?f=15&t=2474