The sensor, or transmitter, is water-resistant and should be placed on a mailbox post or garage wall at a height of 4 feet. Four feet will stop any false signals sent from the ground. The sensor can monitor an area of 20x30 feet. The range to the receiver is 400 feet in open areas. So deduct a bit for the walls in the house and any other variables. The sensor takes a 9V alkaline battery, which is not included with the kit. Just remove the battery-compartment cover and insert a battery in the battery compartment. Replace the battery cover. If you take a look at the back of the sensor, you'll see a hook in the plastic. Screw the enclosed screw to a post and then just hook the sensor on it. The screen should be pointing outwards at the area you would like to be notified if someone crosses. The red LED should illuminate briefly if the path is crossed and the sensor is sending a signal.
There is also a battery compartment in the receiver. Insert three C batteries, which are not included, and close the compartment. Set the switch on the receiver to chime high, low or off. Switch the unit on by selecting high or low and place it somewhere where you'd like to be notified of a visitor. On top of the television is a good place.
The motion-sensing transmitter sends a signal to the receiver whenever the path is crossed. Test the installation by crossing the path of the sensor. You may need a friend in the house to tell you if you have triggered the alert. Because, even though LEDs flash on the front of the receiver in addition to the audible alert, they stop flashing after a minute and it may take you that long to get back in and see the receiver.
You can reduce the sensor-monitoring area by adding tape to the window, essentially "narrowing the vision." If you find the audio too intrusive and just want a visual alert, you can get into the receiver's case and snip one of the speaker wires. This will void any warranty but would be an interesting and fun project.