Do I just skip using 2 of the pins? And since the switch is for 12 V and I only have 5 V power supply, it wont light up?

You only need two pins. Two pins will be unconnected. Did you look at the symbol diagram I posted for you? It might help you understand. Or not… Don’t worry about the switch rating. 12V is more than 5V, so it’s all good.

 

Perfect! It worked fine, except that the LED won't shine, I guess that's because I have a to low voltage.

Anyway, thank you! You really made it clear for me, and like you said, it was super easy.