Wow ... I don't know about you, but I came across RTFM on the programming scene--and it wasn't very polite. Someone would ask a 'begginer' question, and someone else would feel that it waisted their time and they responded with RTFM. Anyway, back to the kinder, gentler first
I don't think covering your hand over it will set off the sensor, you need to cover it with a reflective surface (e.g. shinny metal). The two wires are there for conviniance, either nc (normally closed) or no (normally open). That just means that one will give a '1' when nothing is sensed and a '0' when something is sensed, and the other will be just the opposite. The other two wires are just ground and power, so I think you can handle them.
Stephen