If you wish to extend the duration of a note, select the note(s) with the
Select tool and then choose Duration > Set from the Edit menu that drops down.
  
The dialog you see is in Beats and Steps.
The steps per beat is the number of steps or clock ticks in a quarter note.
This is set by default to 96 and normally does not need to be changed. 

EXAMPLE:
  If you have a quarter note and wish to make it a dotted quarter note, 
  you would need to make the duration 1 beat and 48 steps.

SIDE NOTE: 
  If you import a MIDI file, the steps per quarter will be taken
  from the MIDI file. 

Based on a 4/4 time signature (where a quarter note gets one count and a
measure consists of four beats), the duration values of notes are as follows:

      whole note:         4 beats
      half note:          2 beats
      quarter note:       1 beat (equal to 96 steps)
      eighth note:       48 steps
      sixteenth note:    24 steps


The steps for all possible sixteenth note settings in a measure are 
as follows:

      00    "one"
      24    "e"
      48    "and"
      72    "ah"


If a note's duration is extended into the next beat, the software will
automatically supply the necessary ties.
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