hold ⌘ = create node · ⌥ = create link (overrides the boxes) click select · drag move / resize · ⇧click add + contained · ⌘E expand · ⌘A all · ⌫ delete
Check Create node (or hold ⌘) and drag to create a shape.
Check Create link (or hold ⌥) and drag from one shape to another.
Or load a Sample from the list at top right ↑