The image shows the Assignment section of the Human Task editor.
At the top are the Make Parallel icon, Make Serial icon, Up arrow, Down arrow, Add icon, Edit icon, and Delete icon. The Add icon is selected and a dropdown list is displayed with the following options: Sequential participant block, Parallel participant block, Sequential stage, and Parallel stage.
Below this is a box labeled Stage1. Connecting to this box from below is a block named Stage1.Participant1.