Anyone can watch on adsexchange. Simple trick to filter non-military aircraft. On the top of the screen is the "U" button. Click it on to only see military.

You will only see the ones that are "squawking" a transponder - meaning they are broadcasting their location.

When you click a plane, an information panel shows up on the left side. I learn about the type of aircraft by selecting the "Type" description and googling it.

I learn about the aircraft's history by typing the callsign into the search bar on FlightAware.

I learned about all this by watching MonkeyWerx.