How to create an adventure.

Step One: Ask Two Questions

Every adventure begins with just two sentences: What's the problem? How is it resolved? Write one sentence for each. That's your skeleton.

Step Two: Add Flesh

With your problem and resolution in hand, start adding the muscles and skin: encounters, NPCs, traps, maps, and locations. Some detail should connect back to either the problem or the resolution, but always making the journey challenging.

Example:

Problem: A farmer wears a cursed amulet and becomes possessed, raising the undead. Resolution: The adventurers must return the amulet to its resting place. From that seed, you already have a quest: confront the farmer, deal with undead, recover the amulet, travel to a desert ruin, and return it to break the curse.

Step Three: Scale to the Party

Add details suited to the group's level - weak skeletons for beginners, or giant desert scorpions and hordes for veterans.

That's It.

Two questions, two sentences, and you have the foundation of an adventure.

From there, go deeper - add maps, encounters, NPCs, monsters, traps