You’ll find Reverend Swanson at Flatneck Station to the southwest of Horseshoe Overlook. Head inside the building here to find the Reverend drunk out of his mind while playing Poker. After the Reverend wanders off, opt to sit in on the game of Poker where you’ll be given a tutorial on how it all works. For the Gold Medal, you’ll need to win at least 2 hands of the game and you’ll win the first hand as part of the tutorial. Don’t bet too high to increase the chances of playing more hands should you lose and you should win eventually.
After the conclusion of the game, head outside to track down the Reverend. You’ll find him down the hill and to the right a little, involved in a scuffle with his creditor. Step in and knock the man on his feet by going on the offensive and a person will witness you killing the man. This is the introduction to how the wanted system works in Red Dead Redemption 2. Should a person see you commit a crime, they will dash off to alert the law however should you reach them in time, you can threaten or even beat them into silence. Put this into practice by rushing off after the man and threatening him not to say a word, this will stop the crime from being reported.
Unfortunately the Reverend has wandered off again, this time onto the nearby railway tracks. Head over to him and quickly help him off the tracks by following the onscreen instructions. All that’s left to do now is to escort the Reverend home, sling him onto the back of the Horse and gallop as fast as possible back to Horseshoe Overlook. You’ll need to make the trip, hitch the horse and drop him into his bed within 2 minutes 5 seconds which is more than enough time if you gallop the entire journey.