First, you will want to remove all mildew on the surfaces. When treating mildew, you need to allow the bleach to stay on the surface for at least 20 minutes, or the mildew will not be killed (even though the color disappears), and it can grow back before long. To treat the area, use a 3:1 mixture of water and household bleach, respectively; and leave on for 20+ minutes, reapplying as it dries. Be sure to protect your eyes, breathing and skin during application and rinsing.
Rinse off the area thoroughly; then thoroughly wash the area and rinse again. For best results, apply an interior stainblocking water based primer. Then apply a quality interior satin, semigloss or gloss latex paint, depending on the appearance desired. Some kitchen and bath paints are made with an ingredient to discourage mildew growth. Use two coats of the paint.