keyless entry code

Hi, i have the master code for my keyless entry. How do i go about making a user code or adding a code aside from the master code?

If i type in my code the driver's door unlocks. What do i press to make it then unlock all the doors from the keypad?

Thanks

p.s. IF it matters, i have a 2002 Windstar. incase the instructions differ from one model to another.