Please Help- I got a question here......

Can anybody please explain how to spawn monsters from another unit? an example of this is the huts and houses of gnolls in the map "Warchasers" where they continually spawn monsters until they were destroyed. Please reply A.S.A.P.

Event-
Time- Every X seconds
Condition-
(spawner) not equal to dead
Action-
Create X (unit being spawned) at position of (spawner)

shouldnt there be An

event:
unit enters region

to activate the spawning???

Yeah, that too.
Event-
Unit enters (spawn)
Conditions
Unit equal to hero
actions
turn on spawn trigger

and then one to turn it off when they leave.

How do you put them all up together......is it going to be like this?

Monspawn1
Event-
Time- Every X seconds
Condition-
(spawner) not equal to dead
Action-
Create X (unit being spawned) at position of (spawner)

then make a new trigger:

EnableSpawn1
Event-
Unit enters (spawn)
Conditions-
Unit equal to hero
actions-
turn on "Monspawn1" trigger

am i right????