To track a flight on Flightradar24, you will need either the flight's number or callsign. Type this information into the search bar located, as of August 2015, on the upper-right side of Flightrader24's homepage to locate your flight, according to the site's FAQs section.
Flightradar24 tracks flights around the world, and presents them graphically over a map on their homepage. Through this map, users can track flights and see flight data from up to a week earlier, and paid subscribers can see data from further back, according to the company's official website.
Flightradar24 uses a network of 7,000 receivers hosted by volunteers around the world to pick up and record transmitted flight data, according to the company's official website.