Using external flash memory for program code

Hello,

I am using a Zilog controller ZNEO Z16F2811.
I have an external flash SST39VF020 on my board. The external flash contains
the hex of the program code.
Can someone please explain me how to interface so that the controller executes the program from external flash.
Also, how will the control understand each instruction and jump to the required memory in the external flash.

I am new at this. I would really appreciate some help.