Thanks for contacting World Warfare Support.
You are unable able to send troops to one other at this time, but armaments can be sent between league members. Please upgrade your Commercial Center to level 3 or above. Select the transport option in the Commercial Center and select personal. Then select "choose city", select an "allied city", then select his city, select the armament that you want to transport, and then tap "create". Armaments will then be sent out.