Write some code in the setup() function that does what you want with the LEDs, every time you reset the Arduino the code will run and you can test it.
When it works cut the code out and create a function from it. Then add code in loop() that tests for a button to be pressed and calls that function.
void fireLEDs () {
// your LED code here
}
void loop () {
if (digitalRead(triggerPin) == HIGH)
fireLEDs();
}
Rob