Instructions
Upgrade your hatchery to a Lair. As Zerg, you begin the game with a hatchery; it serves as your source of production. To upgrade to a Lair, click the hatchery, and click "Mutate into Lair." You must have at least 100 minerals and 150 Vespene Gas to do so.
Build an Infestation Pit. After the lair is complete, you must build an Infestation Pit before you can upgrade to a Hive. To build one, select a drone, click "Advanced Mutation" and click "Infestation Pit." The building costs 100 minerals and 100 Vespene Gas.
Upgrade your Lair to a Hive. After your Infestation Pit is up, select your Lair and click "Mutate into Hive" for 200 minerals and 150 Vespene Gas.
Select a drone, click "Advanced Mutation" and select "Mutate into Ultralisk Cavern" for 150 minerals and 200 Vespene Gas. After the drone mutates into an Ultralisk Cavern, select the building to begin producing Ultralisks.