driver for IR led board
In the listing it says: 


  Tensión: DC 12 V


Which means: Voltage: DC 12 V

Which means you need to supply 12 V to this board. Unfortunately no current consumption is mentioned, my educated guess is that this board will consume less than 200 mA so any supply that can output 12 V with 0.5 A (or more) will suffice.

Instead of using only a relay I advise you to get a relay module designed to switch LEDs etc on/off from an RPi (or Arduino). Such a module will contain the relay but also a transistor which is needed to operate the relay. An RPi by itself isn't suitable to drive a relay directly. I recommend a module like this one: