This section remains to be written. For now, please try the following:
select entries with mouse click, or multiple select with CTRL-mouse click
Delete with 'del'
append new children to the current node, by either double-clicking on the canvas or pressing CTRL-RETURN.
append new siblings to the current node, by pressing ALT-RETURN
edit node text by double-clicking on a node or pressing RETURN
change node styles (try "fork-style") using the context menu on a node
To be written.