Create Mode

In create mode, left-click the view to create a joint directly under the root. The created bone is selected.

The lines of the octahedron are called joints

Then click elsewhere to create a child bone of the selected bone.

The thin lines are bones. The thicker one is the parent, the thinner one is the child.

If you want to create a child bone of another parent, click Parent joint. Then it will turn white and become selected.

Then click on another location to create a new child bone.

Even in create mode, joints can be moved, so axes can be stacked as shown below.

You can also right-click a view to display a menu (if allowed in your preferences). The content is the same as when you right-click the bone configuration tree view.