shift registers and row of leds

Hi... I chained 2 shift registers with a bank of leds to attached each and successfully had them light up one at a time. Great.

Now I want to scale up.

I added another shift register and 8 more leds...

I have not been able to modify the following program (which I got off the internet and modified) to correctly light up the leds from 0 to 24 or 32 or 40... I want to understand how to modify the program so that I can chain any number of shift registers and be able to light up the full string or any individual led...

I would very much appreciate the help!!!!

Here it is:

// chain multiple shift registers, each with 8 leds
// light 1 led at a time, from 1 to 24 - blanking out each previous lit led
// then start again
//
//Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
////Pin connected to DS of 74HC595
int dataPin = 11;

void setup() {
pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
digitalWrite(latchPin, 0); //make sure data isn't latched
}
void loop() {
unsigned int outputpattern =1; //stores the output pattern as an unsigned int, that is, two bytes
int pattern_LSB; //the least significant byte (LSB) of the pattern
int pattern_MSB; //the most significant byte (MSB) of the pattern
for (int i=0 ; i< 16; i++){
pattern_MSB = outputpattern >>8; //extract the MSB of the pattern by shifting all the bits over by 8
pattern_LSB = outputpattern & B11111111; //extract the LSB of the pattern by bitwise AND
shiftOut(dataPin, clockPin, MSBFIRST, (byte) pattern_MSB);
shiftOut(dataPin, clockPin, MSBFIRST, (byte) pattern_LSB);
digitalWrite(latchPin, 1); // flick the latch to put the data on the output pins
delay(1);

digitalWrite(latchPin, 0);
delay(100);

outputpattern = outputpattern <<1; // shift the outputpattern left by one bit

}
}

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