Day 3 of Learn Coding with Arduino — connect a push button, read it with digitalRead, and write your first if/else so the LED lights only while pressed.
Day 7 of Learn Coding with Arduino — simplify the button circuit with the Arduino’s built-in pull-up — one resistor less, and toggle the LED each press.
Day 10 of Learn Coding with Arduino — build a night light that switches itself on when the room goes dark, plus a push button so you can override it too.