"Storyboarding" usually means arranging a sequence of images for a film or commercial.
But you can storyboard a novel also, and it can be a helpful way to organize the plot.
 

That's because we don't normally think plot. We have an idea for a story (immigrant boy
founds family dynasty in Nevada wilderness) and a random assortment of mental images
(encounter with a grizzly bear, wild ride to rescue son from kidnappers, gorgeous blonde
swimming nude in icy stream, showdown with eastern gangsters wanting land for casino).
How do we get from these fragments to a coherent plot?
 

Writing a letter to yourself may help, but first try this: Take a stack of 3x5 cards and jot
down an image or scene on each one, just in the order the ideas occur to you. It might look
something like this:
 

-------------------------------------------------------

Jesse rides into town, confronts Caleb Black

about his fraudulent mining-shares deal.

Caleb denies everything, threatens to shoot

Jesse if he talks about it.
-------------------------------------------------------

When you have five or ten or twenty such cards, lay them out in the sequence you envisage
for the story. You certainly don't have a card for each scene in the novel, but you have the
scenes that your subconscious seems to want to deal with.
 

You also have numerous gaps. How do you get Jesse from his silver mine in Nevada to the
deck of the Titanic ? How does Caleb get in touch with the three hired killers from San
Francisco? How does Jesse's grandson respond to the first offer from the gangster syndicate
that wants to build a casino on the site of the old mine?
 

Now you turn your thoughts to just those gaps, and new ideas occur to you. That means
more cards. Maybe some of the new ideas are better than the original ones, so some of the
old cards go in the trash. New characters emerge to fulfill functions in the story. Your
research into Nevada history suggests still more scenes which might go into this or that
part of the novel; still more cards go into your growing deck.
 

The story may eventually end up as a series of flashbacks, but for now stick to straight
chronological order. Maybe the whole story occurs during a three-hour siege of a secluded
mansion; maybe it stretches across a century and a continent. Whatever the "real time" of
your story, you may see that the cards clump naturally around certain periods of the plot
and you see no need for events to fill in the gaps. That's fine; maybe you've found the
natural divisions between chapters or sections of the story.
 

Keep asking yourself why. Why Nevada, why mining, why a gorgeous naked blonde? Don't
keep a scene in your storyboard unless you can justify it as a way to dramatize a character's
personality, to move the story ahead, to lend verisimilitude. If you absolutely must have a
scene in which Jesse's true love Sophia goes skinnydipping in an icy creek and then nearly
drowns, what good will the scene do for the story?
 

Once you have at least the main sequence of events clearly mapped out on your cards, you
can begin to transfer them to a more manageable synopsis or outline.