OK, suppose that you hold the pedal for the whole of bar 1, change it
quickly and hold it again for the whole of bar 2, change it quickly and hold
it for the whole of bar 3 and then release it completely so that bar 4 is
"dry".
 
Visually speaking, you will need the "ped" sign under the first note of bar
1, 2 and 3, and a star under the last note of bar 3. The "ped" signs
indicate that the pedal is pressed down and the star indicates that the
pedal should be raised. You don't need stars at the end of bars 1 and 2
because the "ped" sign indicates that pedal should be raised before it is
pressed again.
 
Select the notes in bar 1 and from the list of staff lines choose pedal
line. Do the same for the notes in bar 2. Finally, select the notes in bar
three and this time choose pedal with star.
 
What you should have is three lines. A pedal line from bar 1 quarter 1 to
quarter 4, another pedal line from bar 2 quarter 1 to quarter 4, and a pedal
with star line from bar 3 quarter 1 to bar quarter 4.
 
The first two lines will just be represented by the "ped" sign at the start
of the line, whereas the ped with star line will be represented by the "ped"
sign at the start and a star at the end.
 
You'll be able to tell if the pedalling is correct because pedalling is
played back.