Once you have a farm, you can hire many of the NPCs throughout the continent of Gemea. To do so, you must first befriend them by giving them food/items that will increase their happiness/friendship towards you. The quickest one would be the questgiver who gave you the first farm, as you can give him Groffle Milk to increase his happiness by quite a bit (or give him around 100 items to increase it by 1% each). Once you reach maximum happiness, you will be given the choice to move them to any of the farms you currently have open.
*Do note: at least for me, there was a game-crashing bug that immediately took down my game after settling the helper into the farm. Save before trying to recruit someone, get the trophy, and then load the save back up once the game is rebooted.