Thanks for the kind words Cristina, I'm glad my stories are helpful to you!
Don't be hard for yourself, you're already putting great work out - keep doing that!
In regards to the menu: you can copy my example and use it yourself.
The only thing you need to edit are the hyperlinks redirecting to the right part of your story.
This guide helped me do it:
You need to publish your story first, before you can fully edit the hyperlinks.
Let me know if you have any questions about it.
Have a great day!