OK, you need the action "Unit - Issue Order Targeting A Point". Use it, for example, this way: Unit Group - Pick every unit in (Units in (Spawn area)) and do (Unit - Order (Picked unit) to Attack/Move To (Center of (Target area)))
if it would be a TD or hero defence than there is a better way to make same strigger as DarkShadow said,but with a little corrections.
Event Unit enters area [needed] Condition Owner of entering unit [needed] Action order entering unit to move-attack at center of [where they need to go]
