"But....but Darth Vader can't be Luke's real father, can he? Is Daddy Darth Vader????" :)
Basically, you need a Dungeon Master who will be the story teller. This person is responsible for setting the stage for the story and guiding the adventurers through their quest. The DM also sets up the encounters with monsters. The DM must know each monster, the Hit Points, the Attack Power, special moves, etc for each monster.
The adventures will listen to the opening sequence of the story by the DM and then they will make decisions on what to do next. The DM will guide the players to what they "should" do, but the DM doesn't "force" them to do anything.
The DM must be able to think on their toes, for players will always try to do something the DM didn't think of...they must be able to quickly act on a situation. Speaking of quickly act, the DM can take their time to figure out what to say next, just don't take like 10-15 minutes, or everyone will get bored.
For the players, try to stick to the story as much as you can, don't go running off and trying to fuck chickens (yes I had a player who wanted to do that all the time).
The players must keep track of their health, inventory and skills. They must know how and when to use certain skills.
I could go on and on, but I see others are commenting now and probably discouraging based on your question, so I will keep this short and hope this is what you are looking for.
Oh, and HAVE FUN, that is the most important part!
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