The curliness of your hair is determined by how your hair is bonded, and the shapes of the bond. Those with naturally curly hair will have a high number of disulfide bonds, and those with straighter hair will have much less. Luckily, you can temporarily change the shape of your bonds to create curls in your hair. Perming your hair chemically changes the bonds, meaning the results will last for a long time, but using a hair dryer can give the same effect for the short term. It's also much less damaging then using curling tongs or straighteners.
Wet your hair. Apply just enough water to wet every strand. Do not soak the hair.
Comb the hair to remove tangles or knots.
Separate the hair into sections, using sectioning pins or hair ties.
Place the round curling brush at the bottom of the section.
Curl hair around the brush, until the brush reaches the roots of hair.
Use the hair dryer to blow moderate heat at the hair as you pull the brush down the hair, forming a curl.
Repeat for all sections.
"Set" hair by spraying with a light hairspray.