Just treat them like any other half hardy annual plant, into a good light position in soil enriched with compost. As a leafy plant, they enjoy a little fertiliser. The one thing you must do is pinch out any flowering shoots which form as this will stop them growing properly. If you keep pinching out the flowers they will form large leafy plants.
Keep a few to grow in pots as they make lovely pot plants, especially the dark red variegated varieties, and you can keep them going well into winter.