World Editor help needed (triggers)

[Rune]

Im currently working on a map idea, but i have been stuck for hours trying to figure out how to make a unit spawn from a specific building every 20 sec of the game. And how to make the spawning of units change owner if the building is captured by another player.
Pls help me guys.

 

[UreDe4D]

check Unit Spawns and spawn unit for your first problem

also capture points and Capturing a building trigger help >< and Capture? for your second one