A new node is created either by dragging an item from the palette on the right of the screen to an accepting cell on the canvas, or by positioning the mouse on an empty cell and selecting a node type from the context menu. The menu shows only nodes that are accepted at this location:

The start and end layers, as well as the left and right swim lanes, are optional. They all accept their specific node types from the palette or from the mouse context menus.

The flowchart frame size can be modified from the context menus at any time by inserting new layers or lanes, and/or removing the unused ones: