connection of an NPN sensor

hello everyone ,Iam stuck in trying to find out how to connect an NPN output sensor
and to be clear I dont know how NPN works ,which means I dont know also how to connect the sensor,
please if any one who knows how this thing works,I need a simple guide on how to connect the sensor in order to receive input signals from it on arduino,this is the sensor :
http://info.bannerengineering.com/cs/groups/public/documents/literature/127816.pdf;Iam still new to electronics so soryy for my questions
Help is very appreciated Thanks

NPN describes the transistor used to drive the output. The NPN transistor is placed between the load and the GND (-). The datasheet shows the appropriate wiring on page 2.

If you want to detect that output, just connect pin 3 or 4 of the sensor to one of the digital IO pins of the Arduino and activate the internal pull-up. This might or might not work as the sensor is intended to be used on higher voltages than the Arduino uses but it's worth a try.

Page 2 of the data sheet. They give a small pictorial what do you need to know? You also have the option of N/O (Normally Open) and N/C (Normally Closed). What exactly were you looking to do with the sensor output? Also keep in mind, per the data sheet, the output limitations.

Using the output for an Arduino just decide on N/O or N/C and use either an external pullup resistor (about 10K) or set your Arduino input for internal pullup.

Ron