Well, cyan is a shade of blue, which is a primary color and therefore can not be created out of other colors. You can add white to blue that you already have, and just keep adding more until you reach the desired shade.
In a computer, and in printing, any colour can be defined by the amount of Red, Green and Blue in it. This is known as the RGB value. These amounts may be measured on a scale of 0 to 255, or in terms...