To draw a straight line within the pose image first select a pose and click on Edit icon.
Then select Straight line tool and click on the spot where you would like your line to begin. Then click on the spot where you want the line to change direction. Continue to click on spots and they will be linked with a straight line. When you finish double-click to end the line.
To reshape the line double-click on it and move little white squares (anchors) to where you want your line to be.
When you finish, change the pose Name or Adaptation accordingly and then click on CREATE AS NEW AND GO BACK TO SEQUENCE.