Final answer:
The series of commands to draw the letter L shape with the turtle pointng towards the top of the screen is BACK 100 RIGHT 90 FORWARD 50.
Step-by-step explanation:
The command series to draw the shape would be:
BACK 100 RIGHT 90 FORWARD 50
This series of commands will move the turtle 100 steps backward, then turn it 90 degrees to the right, and finally move it 50 steps forward. This sequence will create the letter L shape when the turtle is initially pointing towards the top of the screen.