People have done tutorials for that, just sayin.
Warning. If you read ahead, you'll take the risk of getting more confused. Make sure you want this or if you'd rather follow my steps from the last post without further digging into this.
So. Actually, the concept of neighbouring zones pretty much self-explanatory. If zones are neighbours, that means that they are linked in the eyes of the AI commanders. Lets say you have 2 CPs, one is owned by each team, they are two-way neighbours (blue line in the Editor). Both AI commanders will now give the order to attack the CP they don't own.
If they are one-way neighbours and connected by a red line in the editor, only one AI commander will see the other CP as a valid target and issue attack orders. The othe AI commander will now only see his owned CP as target and therefore issue a defend order.