a minimal version, not tried to compile with leds on pin 3,4,5 should get you started.
int ledpin[3] = { 3,4,5 };
int ledcount = 3;
int currentPin = 0;
void setup()
{
for (int i=0; i< ledcount; i++) pinMode(ledpin[i], OUTPUT);
for (int i=0; i< ledcount; i++) digitalWrite(ledpin[i], LOW);
}
void loop()
{
if (digitalRead(buttonpin) == HIGH) // assuming buttonpress => low -> high
{
digitalWrite(ledpin[currentPin], LOW);
currentPin = (currentPin + 1) % ledcount; // wraps ledpin around
digitalWrite(ledpin[currentPin], HIGH);
}
delay(1000);
}