In the left navigation pane are the Basic Info, Operations, Callback Operation, Headers, Request-Headers (which is selected), Response-Headers, and Summary tabs. In the middle of the page, the following fields are displayed.
In the middle of the page are the SOAP Headers (which is selected), Standard HTTP Headers, Custom HTTP Headers, and Custom SOAP Headers.
Below this is the Detach button. Below this is the Header Name section, which includes the inputHeader value.