I have a writing tendency where I get straight to the point, especially when I already have an amazing storyline. The ending goes especially quick. I need to figure out how to move the story along, in the beginning, to get to the end. But I don't know how to properly do that.
What are ways I can move my story along without making it boring, so I could increase my book length?
Most first drafts are too long, and improvement usually involves removing a lot; and yet many beginning writers think they should make their story even longer. But suppose you've not made a mistake. If a story has the potential to benefit from a longer draft, I think it needs to be done from scratch, not by adding words to what you already have. In other words, regard the existing version as a very, very long plot outline, or as part of one. (Read "plot" as shorthand; characterisation, setting etc. can benefit from plans too.)
If a hard drive failure meant you had to write the whole story again, remembering roughly what happened before and what worked well, you'd probably think, "Oh, and while I'm writing it all over again I may as well flesh out X". Such considerations are why I say the current version is part of an outline.
But as I wrote before here, a second draft can also be longer despite, or even because of, fewer moving parts, with what remains being better able to grow to its rightful size. So even if a second rewrite results in a longer work, I can't say now why it did so. Nor, for that matter, can I say whether the length increase is prudent. I'm leaving that judgement to you.
Write the length you need to tell your story.
If it turns out to be a short story or a novella, so be it.
Instead of taking longer to tell the story, maybe what you need is to tell a story that spans more time. Or one that looks at more points of view.
But first, working on improving your writing overall. Take a class. Join a writer's group with other beginners. Practice writing lots of short things to increase your skill set. I had to edit some very basic stuff in your question. Be sure you have the basics down before attempting something as ambitious as writing a novel or longer story.
A shepherd boy was bored of just watching sheep, so he cried out that there was a wolf, and the people from the nearby town came running to save him, but were angry when he laughed at them and called them all fools. The next day a wolf really came, but nobody listened when he cried out, thinking it was another joke at their expense, so he was eaten.
The reason people often react poorly to the question of how to make a story longer is that we all have bad experiences with "filler" chapters and episodes and scenes, which really feel like their only purpose is to get to a required length-quota. But this seems like a sincere question. Let's build from the story above.
The fundamental theme of the boy who cried wolf could span a brief paragraph, or it could be much longer. How much longer? I've seen it rendered as a couple of pages. If I kept only the central idea, I could likely stretch it out to fill a novel. At that point I probably wouldn't be writing about a literal wolf or a literal shepherd, but perhaps about a young accountant who rises to importance by (incorrectly) alleging corruption and destroying someone else's career. Later he discovers real corruption, but it the midst of the new investigation, the skeleton of him being a liar (or maybe only careless?) in the previous investigation destroys his reputation, which actually saves the villain he was pursuing.
Throughout this framework could be woven the courtship, marriage, and budding family life of this accountant and his high-school sweetheart, who he'd met again unexpectedly - and how the woman he cares for is tragically dragged down with him. There would be relationships with coworkers, too - perhaps tainted from the beginning by the main character being constantly nervous that others might realize that maybe the incident that raised him to importance in the first place could someday turn and destroy him, as it eventually does.
If I took 300 pages to describe a bored shepherd-boy's afternoon, and a crowd of people running to his rescue - and then not running to his rescue - it's unlikely that I could put in enough details to keep even the most charitable reader's interest. You could stretch the account's story that far.
In The Neverending Story, by Michael Ende, the Grograman talks about having just come into existence when Bastion wished for a companion, but also having existed for thousands of years. While causality in-story should make sense and be linear, the cause of a character's existence, or a problem, from your point of view as the author, is to make interesting tension, and to serve to build towards whatever it is your story is about. Events in a story must serve some general idea, though, or they're off-topic and don't belong. Nobody cares if the shepherd boy was even wearing a watch, though what kind of watch the doomed-for-the-fall accounted wore might say something about his character, and then it would be fair game).
If your stories get to the point too quickly, you do need to weave in something else. But the details must serve the story you're telling. And not every telling of every story will bear as much digression or detail.
I have the same issue, and I've come to realize I'm conceptualizing it wrong. It's not that my books are too short, it's that they are missing important things that make up a full reading experience. For me, it's often mainly visual details. My books tend to be dialogue focused, like a screenplay, as opposed to possessing the rich fabric of sensory detail featured by most beloved books.
You may also be shortchanging character development, important scenes, and subplots in your headlong rush to make it to the end. A good rule of thumb is that your late drafts should be editing down something bigger into something tight and trim, not trying to expand a skeleton into a full body. (That's the job of your early drafts.)
I would encourage you to make the same transition I'm trying to make in my own work. Become less goal focused, and live more in the pleasures of each scene of the book, rather than just making it a headlong race to the end. Unless you're already under contract to deliver something by a certain time, there's no real value to getting there quicker, if it doesn't have the quality. A rushed book is like taking personal notes --it means something to you, but it won't live for the final audience. You need to write for them, not you.
What you really shouldn't have is what people have already said: fillers, and pointless digressions.
Unless it adds to a story, like Grandpa Simpson. he always has pointless digressions in his dialogues.. but that's just to give that character some extra character.
