How do you change a front wheel drive car to rear wheel drive?

With great difficulty.

With enough time and money you can change a front drive car to rear drive. The question becomes "why bother"?

Unless you've got your own workshop, and a donor car standing ready, or there's something real special about the car you want to do this to, the sensible thing is to sell the FWD and use the money to buy a RWD car instead. A lot less hassle, and probably cheaper too.