ir = lum >> 16;// what does this mean cant get the syntax?
That is a binary shift operation. It shifts the value right by 16 bits (equivalent to a divide by 65535)
full = lum & 0xFFFF; //what does this mean cant get the syntax?
That is a binary masking operation using a logical AND (&). It masks off everything but the low order 16 bits.
Also the sensor is giving me 0 luminosity. Even when the sensor is disconnected and i run the code it gives found sensor.
Post photos showing all your connections and we'll take a look.