hello i have the RGB controller(VM151) nice thing but i cant connect a RGB LED to it
because a RGB LED use common cathode- as his com and not the plus+ 
i like to no wat i can do to make it work wit the 4 pin RGB led
You need to use a common anode RGB led (most RGB leds are common anode) or an 6-pin RGB led.
Please note that you cannot connect an RGB led directly to the unit, you will need to put a current limiting resistor in series with each colour.
You can if they are common anode, like 99% of all available RGB leds.