C-3PO and R2-D2 are telling the story that we see in the movies to the Whills. The opening crawls are parts of the contents of the Journal of the Whills. We also know that the Whills taught Qui-Gon Jinn how to become a Force Ghost.
Early on in the development of Star Wars, the Whills were to be the only ones who could use The Force and they would give advice to the characters.