In this overview the participants are displayed, which can be selected in notifications as Reporter and in report files as Sender and Originator. See the sections Services/Capital and Create report file for this.
With the buttons above the overview you can create new participants or delete them. When creating, the company of the last entered participant is selected. This serves just the purpose of simplifying the data entry. For creating, just click on the participant in the overview. In both cases, the page is loaded, which is described in section Create participant.