There are a few different ways to manage, set up, and share alerts. You will need to be logged into your account to complete any of the following.

The first option is to click on the My Alerts link at the very top of the website, on the same line as your username. Click on My Alerts to get to the Flight Alerts section of your account, then click Set up New Alert at the bottom right. Fill in the form according to your specific preferences and needs. If you'd like to share alerts with authorized users or for unblocked aircraft, you may do so in the third section of the form, "Where should we send the alerts?" Select the check-box labeled Share this alert with a friend and enter their email address. These recipients are not required to hold a current FlightAware account unless the aircraft is blocked, in which case they would need to be an authorized user added to your Global Account.
The second option is to hover over your username at the very top of the website, and click on My Account from the drop-down menu. Once your account settings page populates, click on the gray Flight Alerts tab. From here, follow the instructions for setting up an alert mentioned above in the first option.
The third option is to create an alert directly from the flight tracking page. On any individual flight tracking page, this a Get Notifications button in the upper-right-hand side of the page. This will allow you to create and share alerts similar to the methods above.

FlightAware Global Product Guide

Global Account Name: The name associated with your FlightAware account.
Custom Airport Name: Specify a unique and identifiable name for the custom airport.
LID (Local Identifier): A distinctive five-character code for local identification.
Longitude: The longitudinal coordinate to locate your custom airport geographically.
Latitude: The latitudinal coordinate to accurately place your custom airport on the map.
Elevation: The height (usually in feet or meters) above sea level at which the airport is located.
Timezone: The standardized time zone in which the custom airport is situated.