If you pick up a random bestselling book, you'll find at least one conflict in the contents. Without conflict, a book would never be considered good. When you're reading a good book you'll find yourself wishing and hoping that the conflict will be solved; this keeps your attention. You won't want to stop reading until you've reached the end.

For the people who don't have any idea what to write about, this will be one of the harder steps. My advice to you is to pick a conflict that you've faced yourself or a conflict that someone you know has faced. You could also choose an object and think of a conflict that could arise with it. Or you could choose something that would make you uncomfortable or sad. My last help on this matter is that you could think of a goal a character would like to achieve. The conflict will be how to reach this goal.

If creating conflict is too complicated for you, just borrow a conflict from another story to practice. If you decide to make your story public, don't forget to mention which story you borrowed it from (fan fiction).

You need one main conflict that starts in the first chapter and keeps getting bigger and bigger until the very end of the book, when the conflict is finally solved. During the book, parts of this conflict could be solved, while new problems arise to complicate the lives of your main character even more.

You could choose some side conflicts for your character to deal with as well. These don't have to span throughout the entire book.