If you don't know how to manage 3 parameters then this doc won't do any good. But good luck in your path toward success!! 
      
                  
                
                
                Parameters
                
                  - 
                    Brightness (Percentage (-100% - 100%)) :         The absolute value of colors (tones) lightness/darkness
      
                  
- 
                    Contrast (Percentage (-100% - 100%)) :         The distinction between lighter and darker areas of an image
      
                  
- 
                    Gamma (Percentage (-100% - 100%)) :         Adjusts the mid-tones from tonal scale, but keeps the white and black intact
 Gamma may seem a more natural way to change the contrast while keeping an adequate brightness
Presets
                
                Standard Presets: Light Contrast, Medium Contrast and Hard Contrast