Hey Wayne,
I think the manual covers it pretty well?
Right clicking brings up a menu that allows
the draw track to be saved into a new file (and subsequently added to the
active list). IMPORTANT: if you do not right click and use Save As... the
drawn track will not be saved.
To answer your question, you can't right now save into a current layer. However, that's definitely high on the todo list. Another user requested that function, and I'd like to see it to.
Thanks Wayne.