if u go to track view (5th icon in from top left)
at the top right you should see edit mode select region edit
change from draw mode (pencil icon) to select mode (dotted square with arrow icon)
you can then highlight and copy and paste by going to edit at top of screen there maybe short cut keys for that also u have to move the scroll line that moves along the screen (follows the song) to where u want to paste too
should be enough to get u started its quite easy when u get used to it pretty flexible too
you can't overlap tracks as it replaces the data with what u put over it