Instructions
Speak with Gus by dropping through the trapdoor south of Hetty̵7;s house in Rimmington. He explains his plight: his three crates have incorrect labels and he needs help fixing them.
Check the Newt and Toad crate first. Because all of the crates are incorrectly labeled, whatever animal you pick from this crate is the animal with which it should be labeled. For example, if you pull a toad from the Newt and Toad crate, label it with a Toad sticker.
Place the other single animal sticker on the other single animal crate. Following the example given above, you would still have a Newt sticker to place -- stick it on the crate with the Toad label.
Place the Newt and Toad label on the remaining box. Once the boxes are labeled correctly, you can take a newt from the Newt crate and bring it up to Hetty.