When to use the prepositions ABOUT or ON

Friends,

How do I know whether I have to use the preposition ABOUT or ON?

Examples:

- There are no instructions on how to do this.

- Where is my story on James Stweart?

In the sentences above, why can't we use ABOUT instead of ON? What is the difference between these two prepositions? What are the rules?

Thansk very much for your attention, guys.

brunces