Arduino Basic Timer Help (12V system)

So I am pretty new to arduino hardware, but know the language enough to code up something I need for a coming project! What I am trying to do is use a 12V battery to power a strip of LEDs that will light up for 13 seconds when I press a button. My confusion here is the circuit, as I need a compact build to wear on a costume and finding a way to use the arduinos with 12v as I require the 12V brightness. Any suggestions on a circuit or where I can look?