How to start using RS232?

I use IR with Global Cache and works ok but I would like to use RS232 to provide better installations.

What I need to buy to control a receiver using RS232 port? What kind of software and hardware do I need to buy?

And how to program the port? How to send the code? From where?

About the format of discrete codes, how to work with RS232? Is there any tutorial that I can read to learn from the ground about RS232?



Thanks.