Help adding 3 more on/off switches so that I can control 4 LEDs
Use arrays, one for switches, one for leds. I don't see the code for leds in your code.

Note that you need 8 pins (4 for switches, 4 for leds).

Initialize them, e.g.

int switchPins[] = { 2, 3, 4, 5 }; 

Same for leds

int ledPins[] = {6, 7, 8, 9};


To access them, use a for loop:

for (int iLed = 0; iLed &lt; 4; i++)
{
   digitalWrite(ledPins[iLed], HIGH);
}


Because 4 might be used a lot, consider them making const or define:

#define NR_OF_LEDS 4

for (int iLed = 0; iLed &lt; NR_OF_LEDS; i++)
{
   digitalWrite(ledPins[iLed], HIGH);
}


or use the length of the array

for (int iLed = 0; iLed &lt; sizeof(ledPins) / sizeof(int); i++)
{
   digitalWrite(ledPins[iLed], HIGH);
}