Guild Rights and Treasury
Not all GvG actions are available to all players. The following actions require the guild member to have the "trusted" right:
Unlocking a defending army slot.
Replacing an army
Deploying or deleting a siege army
Grant freedom (you can only do it 4 times per day)
As your guild conquers and expands its territory, goods cost rise for siege and defensive army slots. Your whole guild may need to contribute goods to pay for new army deployment and unlock defense slots, and this is where the guild treasury comes in. When you attempt to place an army, you are first taken to the unlock screen, where you can contribute to - your guild's treasury.
In the image below, 30 iron and cloth are required, and as you can see that they are already available in your guild treasury, because the number is shown in green. Also needed are ebony, jewelry and limestone, which the guild need to collect and pay in order to unlock this slot. Buttons beside the good requirement show what you as a player are able to contribute: in this case, 15 jewelry and 15 limestone. And you could also use Diamonds to purchase ebony for your guild.
Only when all required goods are available can the slot be unlocked.
You can also donate goods to your guild's treasury whenever you feel like it in the Treasury screen. On the image below, you can see that that guild is unfortunately not very rich: