Mutiple LED. Switch button. Advice on coding

Projects General Guidance
1

int inpin = 2;
int outPin = 13;

int state = HIGH;
int reading;
int previous = LOW;

long time = 0;
long debounce = 200;

void setup()
{
pinMode(inpin, INPUT);
pinMode(outPin, OUTPUT);
}

void loop()
{
reading = digitalRead(inpin);
if (reading == HIGH && previous == LOW && millis() - time > debounce)
{
if (state == HIGH)
state = LOW;
else
state = HIGH;
time = millis();
}

digitalWrite(outPin, state);
previous = reading;
}

This is the code i'm using to turn the LED on pin 13 ON(arduino UNO) and off the with push button. where can I include the serial print code to monitor the LED state or the Pushbutton state. Also I want to start a timer when my LED turns on and the time to stop when LED turns off. How can I do this? Also if i want to use another LED and another Pushbutton how do i alter the code?g

2

FarazK:
where can I include the serial print code to monitor the LED state or the Pushbutton state.

Ask yourself "Where in the code do I change the LED state?" and "Where in the code do I detect when the pushbutton state has changed?" That is where you put your Serial.print() code.

FarazK:
Also I want to start a timer when my LED turns on and the time to stop when LED turns off.

Ask yourself "Where do I change the LED state to ON and where do I change it to OFF?" Put code there to record the ON time and Off time in variables. When the LED turns OFF you can subtract the ON time from the OFF time to tell how long the LED was ON.

FarazK:
Also if i want to use another LED and another Pushbutton how do i alter the code?

Mostly you duplicate parts of the the existing code using new constants for the pins and new variables for the state. If you have three or more buttons it is time to learn about arrays.