Flat irons are actually used to straighten hair. In order to curl hair, one should use a curling iron. First, allow the iron to heat up to the appropriate temperature. Next, take a segment of hair that is not too large and slide the hair under the clamp on the iron, leaving about 1′ of hair sticking out past the clamp. Then, wrap the hair around the iron, making sure not to bring it too close to your scalp. After you have wrapped your hair around the iron, leave the iron in place for 60-90 seconds. Finally, slowly unwrap your hair from the iron and repeat the process as desired. Please note that if your hair is heavily processed, heated styling tools can damage your hair further.