Looking at your plants label, determine what its genus isthat is the first name on the tag. How much light your plant will require will depend on the type of orchid it is. Below find light requirements recommended by the American Orchid Society:

Cattleya --Medium to High

Cymbidium --Medium to High

Dendrobium --Medium to High

Masdevallia --Low to Medium

Miltonia --Medium

Odontoglossum --Medium

Oncidium --Medium to High

Paphiopedilum --Low to Medium

Phalaenopsis --Low to Medium

Vanda --Medium to High

Low Light = 1,000 2,000 foot-candles, two hours of filtered sunlight per day, 14 hours of fluorescent light within 8 inches of the tubes. These plants can be grown indoors under indirect light or outdoors under shade.

Medium Light = 2,000 3,000 foot-candles, four hours of sunlight per day, 16 hours of fluorescent light within 6 inches of the tubes. Outside, moderately sunny windows or under lights would be suitable.

High Light = 3,000 4,000 foot-candles, six hours of sunlight per day, within 3 inches of tubes, near the center of the fixture. In a sunny window or outdoors would be ideal for these plants.

Foot-candles is a standard measure of light for plants and can be determined with alight meter.

Source: Your First Orchid, AOS, Stephen R. Batchelor