Based on the provided reference, creating a creeper farm involves specific steps centered around manipulating mob spawning mechanics:
The core steps seem to include:
- Trap Doors: Placing trap doors across the main floor of the farm.
- Slabs on the Roof: Placing slabs on the roof of the farm to prevent zombies and skeletons from spawning in that area, thus increasing the creeper spawn rate.
Because the provided source is so minimal, a more complete answer cannot be given without making significant assumptions and extrapolations, which is avoided by design.
