When an alliance member needs help it will appear in the consulate. Every member can get a certain amount of help for their task, and members can only help once per task. The amount of time for the task will be reduced every time another member helped. You can either help all by clicking on the red bubble above the Outpost or selecting that option in the Consulate or you can select the player you want to help in the Consulate and help directly.

In case you need help, you can click on the bubble above the building that is involved in the task you need help with.

You will gain alliance points for helping, although you can only be rewarded a certain amount of points per day.