The best way to find out if it is a real painting or not would be to take it to an appraiser. The American Society of Appraisers' website (http://www.appraisers.org) can help you find an appraiser in your area. many (but not all) appraisers have certain hours during which you can bring an item for appraisal at little or no cost. If there is a Sotheby's office in your city you can also make an appointment for a no-cost auction estimate.
