Adding mobs into zones...

[Crayeon]

Ok i am a noob (omg, how many times have you guys heard that =P)
But! i have been searching the fourms for a bit now,
Anyway my question is:

How do you add mobs into a zone? (example: I am trying to replace
all of rivervale with enemy npcs, and failing horribly)
I want them to be stay in there i want them to respawn etc etc...

I have my server up and going and now i am trying to customize zones.
This probably is a dupilcate post somewhere and if there is another
thread explaining all of the i appologize now.

Please Help ^_^