Hi enbar vodevoz,
I think what you want to know is the dimming function of this device. There're three ways for dimming. If you want to use the PWM dimming, you can apply a PWM signal to SEL pin.
The average output current will be modulated by the duty cycle of the PWM signal you applied. For example, if the nominal output current you set is Iout, then after dimming with PWM signla, the output current will be Iout*D. ( D is the duty cycle of the PWM signal)
I can't help more with your limited imformation, so if you want the detailed design, you need to show me the details.