One of the most important parts of a book are the characters. If you don't have a character your reader will fall in love with, they will put the book down and not touch it again.
So, one of the biggest challenges an author has is how to create a character that will keep the reader from putting the book down. Now, that's a pretty tall order. You've got to create an entire person and effectively bring the character to life through words.
How are you supposed to do this????
The first thing you have to do is define your character. Give your character a name, a brief backstory, a basic appearance, and a core personality. For example, I'm going to create a character named Julia. I think she is a little girl of ten or twelve who discovers a strange egg in her backyard ... which glows red. As for basic appearance, I think she's of average height, has blue-green eyes, ginger hair, and freckles. Lots of freckles. As for core personality, she's sweet, and curious, has an overactive imagination, and loves big words that she does't know what the mean exactly but she uses them anyways.
Now that I have a basic character (and the start of my story, girl finds egg in backyard) I need to go in depth. If I want to, I can give Julia a middle and last name ... how about Anna and Roma. Julia Anna Roma. That has a nice ring to it. I can go in depth with her backstory. Because she has an overactive imagination, no one believes her when she finds the egg. Also, due to all those freckles, I would deem it a safe guess that she spends a lot of time outside. A great idea is to take Julia and interview her. Ask her a list of questions and see how she answers. It doesn't really matter what sort of questions you ask her, and it doesn't matter how random they are. Indeed, sometimes the random questions can give you the best insights on your character. For instance, I could ask Julia what sort of shoes she wears, and when she tells me she wears a pair of hand-me-down shoes that were originally bought for her cousin 10 years older, and that they're severely beat up, and that she has the shoelaces decorated with beads and glitter from school, I learn that she comes from a somewhat poor family and that she's very creative. Don't forget to give her flaws (readers hate flawless characters) but make sure the flaws make sense for her character.
And now for the really fun part. Bringing Julia to life through words. There are three ways, which I call the three A's: Action, Appearance, and Articulation. Action is what she does. If she tosses her bookbag on the couch as she dashes outside, it shows a definitely different personality than if she placed her bookbag carefully on the couch before she calmly went outside. Appearance is what she looks like. Having unkempt hair and a shirt covered in glitterglue shows a very different personality than well kept hair, and a clean shirt. Articulation is what she says. "Hurry, Hurry, there's a giant in the yard!" Julia exclaimed, interrupting her mother on the phone, shows a very different personality than, Julia waited for her mother to get off the phone before she calmly informed her mother, "I think I saw a giant in the yard."
Of course ... Julia's just the main character! Julia also has a mother, a father, older and younger siblings, friends (both real and imaginary) and of course, the all important whatever-that's-in-the-egg. Guess what? You've got to define their characters, too. Just because they aren't the main character doesn't mean that you don't have to know pretty much everything about them too! A well defined supporting cast is just as important as a well defined main character.
And what if there's a villain who wants the egg so he can take over the universe! You've got to define him too!!!! Give him backstory (why he became a villain) and physical characteristics. Mr. Fiery may have once been a little boy in a situation (overactive imagination, poor family ...) much like Julia, but then he discovered the egg, and it corrupted him, and now he's collecting all of the eggs like it in the universe in hopes that they'll give him great power (which they do).
And soon, as you come up with your characters, you'll find you have a great story.