Workers are not resources, but they are produced on villages just like resources are produced on other terrains. Just as with any Produce action, first pay the full cost on all exposed red boxes on the Produce action, then Produce the worker(s) by taking the meeple from your Player Mat (left to right).

You may choose not to produce a worker, as it can increase the cost of future Produce actions. Once produced, workers may never return to your Player Mat.