In several decades, the core idea behind the Green Lantern origin (we’re referring to Hal Jordan in this case) hasn’t really changed. So here’s a quick and simple primer!
The clip (thanks to Superfriends) pretty much gives you the essential origins of Hal Jordan. Generally when the origins are expanded, its on the side of Abin Sur (the purple alien in the clip.) Various origins such as Geoff Johns’ Secret Origins expands on the fact that Abin Sur was transporting Atrocious, Emerald Knights (the latest DC DTV) hints at something similar, the movie seems to deal with Parallax, and various others just don’t give much of a reason why.
So there you have it, Green Lantern origins 101 in less than 5 minutes!