Electronic Help for Newbie.

Hi, I have a digital recording module that is activated by a push button. I just bought a PIR Motion sensor by Parallax and the Arduino Uno. I just soldered my first set of wires together a week ago and am lost. Can the push button on the recording module from radioshack be replaced by something? Any help would be greatly appreciated. Maybe I need different components. My son wants his valentine box to play the sound recorded on the recording module when someone puts a valentine in the box. My plan was to have the PIR in front of the slot facing up and when they reached over the sensor, the sound would start. Thanks in advance for any help you can provide.

Firstly can you get access to the solder pads on that push button? If so then you can try probing the voltages with a multimeter to see what they are with the button pressed and not-pressed. That information will be handy in deciding how to proceed.