Chief
A chief is an ordinary that runs as a band across the top edge of the shield. It usually covers between a quarter and a third of the shield's height, drawn wider when it carries charges of its own. In chief also means the upper part of the field.
A chief often carries a second idea on top of the main design. Many Italian arms added a chief with the arms of Naples or the Holy Roman Empire to show which side a family or town took. The Swiss town of Baden pairs a black pale with a red chief. In blazon, the chief is named after the main charges on the field.
Add a Chief from the ordinaries on the Shield tab of the coat of arms maker, then click it to set its tincture. A row of small charges such as mullets or scallop shells fits nicely in it. See the heraldic divisions guide for how a chief differs from a per fess split.