When using a piggyback adaptor on a H1 globe, as the globe generally will only have a positive pin and pick up ground elsewhere, above are 3 alternate ways to pick up an earth/negative.
Working our way from left to right, you will see the first line reaches to the collar around the globe. Hard to describe using graphics, but this tab is usually located at the opening and is attached to the headlight itself, not the globe. In some vehicles, you will notice the tab/tabs in a hard to reach location. Essentially this is just earth so you can attach the negative spade from the piggyback straight to one side and this should get you sorted.
Alternatively, if access is too tight, you can attach the negative spade to a raw metal surface as the earth on the chassis or if within reach, straight to the negative terminal on the battery.