To make a dried ghast in Minecraft, there are three main ways:

1. Finding one naturally : Dried ghasts spawn in the Nether, specifically in the Soul Sand Valley biome near bone block structures or Nether fossils. There is about a 33% chance of a dried ghast spawning near these bone blocks, and it can be mined easily with any tool or by hand to collect it.
2. Crafting the dried ghast : The crafting recipe requires 8 ghast tears arranged around 1 soul sand block in the center on a crafting table.
3. Bartering with Piglins : By giving gold ingots to Piglins in the Nether, there is a chance to receive a dried ghast as one of the barter items, though this is less reliable with about a 2.13% chance per barter.

Once obtained, the dried ghast block can be used to create further mobs like the ghastling and happy ghast. The dried ghast block can be placed anywhere and hydrated with water to start this transformation. This summary covers all current methods to acquire a dried ghast in Minecraft 1.21.x and related versions.