Preparing to Write a Book

I am a 25-year-old woman, and a passionate student of spiritual teachings.  Since I opened up to Spirit, I have always tried to remain a grounded student, aware in the present moment.
I feel as though Spirit is guiding me to write a book. Currently written is the title, outline, as well as access and experience to all the information i need.  I guess the one thing i am lacking right now is belief in myself…my youth and lack of a university degree are my biggest issues.  And that really is impeding my progress thus far.
So, my question for you is:

If you feel the Universe is pointing you in a specific direction, placing the opportunity to share your thoughts and ideas – what inspires you – with others in written form, how do you know for sure? How do you know the best way to present your teachings to other people?