The simple setup procedure is:
1) Go to the 'Configure' tab and enter your name and your iPhone number.
2) On the 'Configure' tab, notice that the default Update Frequency is 10 min. In other words your location will be sent to the contacts you add every 10 min. You can set this to a minimum of 5 min. Change this if desired.
3) On the 'Configure' tab, the Desired Accuracy is set to 200 meters. This is the accuracy of your location. You can set this to a minimum of 10 meters. Be aware that setting this to a low number will require more battery power and time for the iPhone to acquire your location.
4) On the Start/Stop Tab: Press the 'Add' button to select phone numbers and/or email addresses from your contact list. For cell phone numbers, select the cell phone carrier on the detail screen. [ Press the '>' on the far right of the screen. ]
5) On the Start/Stop Tab: Press 'Start' to start sending your location. Press 'Stop' to stop sending your location to your selected contacts.
Here is an example of the message that will be sent to your selected contacts:
[Your Name], [Your phone number], is here: http://maps.google.com/maps?q=30.037557,-89.976139 [Accuracy = meters.]
Where [Your Name], and [Your phone number] are what you entered on the Configure Screen.
You can background the app and it continues to work. Therefore, I'm required to state that:
"Continued use of GPS running in the background can dramatically decrease battery life."
But, the app is written to minimize the time the GPS hardware is enabled.