How can I use an ADS-B receiver to make my aircraft visible in Flightradar24?
ADS-B is broadcasted by many aircraft and contains flight and aircraft information. This can easily be received and decoded, either by dedicated devices or a simple 20 bucks TV USB dongle. All information is then sent to flightradar and other sites by the members of their community. (there are also other sources for their data)

However, once ADS-B is broadcasted and received by any receiver working for flightradar, the aircraft appears on their map. There is no need to register your self, in fact, you have to opt-out if you prefer to be invisible.

Now, you write about a receiver, and also a short visit of the product page shows that your device is a receiver only. Together with the built-in GPS it might just warn you about other near aircraft (which do broadcast ADS-B). You will need an ADS-B sender to find yourself on flightradar. 

In the US, ADS-B Out is required to be installed (by Jan 1, 2020), it cannot be a portable unit. ADS-B In can be a portable unit.