Instructions
Select the house you want the Townie to join. Enter the house.
Click on the avatar of the Sim who knows the Townie. Click on the telephone and instruct the Sim to call him. Talk to the Townie to increase the relationship to friendship status. If the Sim doesn't know any Townies, purchase a computer from the shopping menu. Tell the Sim to chat with people online to meet Townies. The Sim can also take a taxi to community lots to meet Townies.
Call the Townie and invite him over. Greet him when he arrives. Instruct the Sim to do two to three positive interactions with the Townie, such as talking, playing or joking.
Select the Townie. Look for the option to move in on the social pie menu. Click on it when it appears. The Sim will ask the Townie to move in with him. If the Townie accepts, he moves in with a share of money. If you want the Sim to marry the Townie, do romantic interactions until they fall in love then choose "Propose" from the pie menu. Click on the Townie again to conduct a marriage ceremony.
Click on the Townie's avatar once he is a part of the house. If you want to move him into his own house, click on the newspaper or computer and instruct him to find his own place. He will move out and appear in the family bin on the main neighborhood screen. Click on his image and place him in a house.