Fallout 4 introduces the ability to build up settlements. You’re able to provide shelter, food, and water for others and they can earn their keep around town to flourish a sprawling community of survivors.
When you set up some of the structures around your settlement, you’ll find that a message pops up urging you to assign a worker to it. This is a reminder for you to do this as well as a helpful hint that it won’t work without someone assigned to it. Once again, Fallout 4 doesn’t do that good of a job of showing you how to do this.
To assign a worker to something, say, a guard post, you first go into Workshop mode. Approach the person you want to assign to the guard post and hit the appropriate button for “Command.” From there, go to the guard post and hit the appropriate button for “Assign.”