What is Sophocles trying to tell his audience about the concepts of Fate and Free Will?

In “Oepidus Rex,” What is Sophocles trying to tell his audience about the concepts of Fate and Free Will?
potential outline :
I. Introduction
A. Context
B. Thesis
II. Scene 1
A. Summary
B. Analysis
III. Scene 2
A. Summary
B. Analysis
IV. Conclusion
A. Overall Message
B. Final Thoughts
suggested link of the play :
http://abs.kafkas.edu.tr/upload/225/Oedipus_the_K