The ranked games can be kind of a doozy. All you simply need to do, as the description states, is play one. You should play it all the way through until you either win or lose/get knocked out... so simply decide you need to cash out before you lose.
The best example of the intensity or scope of ranked games come from these two videos. One shows how you can go from nothing to everything by YouTuber "Fabiano Farhat." The other shows the length and sheer scope these games have by YouTuber "122017 Gaming."