If you go to the link below, enotes has a very detailed summary of the story. I will go ahead and give you a broad summary.
It is basically about Ichabod Crane, a schoolteacher and singing instructor from Connecticut. He's well-liked by his students and their families. He does chores for the families in exchange for food and entertains them with stories, especially about witchcraft and magic. One such local story is about the ghost of a Hessian soldier who rides through the countryside looking for his missing head.
Crane dreams of marrying one of his students, Katrina Van Tassel, and starts to court her. Because her family is wealthy, Katrina has other men who court her as well. Ichabod's biggest rival is Brom Bones, a strong, handsome, clever man. Ichabod refuses to fight Brom, so the latter suitor decides to play practical jokes on Ichabod.
Katrina's parents have a party, and we think Ichabod asks her to marry him but that she says no. On his way home, Ichabod is chased by the headless horseman and is knocked unconscious. He's never seen or heard from again; all that is found is his hat and some of his possessions. There are hints that Brom Bones could be responsible for Ichabod's disappearance, but the women feel he was the victim of the headless horseman.
I hopes this helps. As I said earlier, the link below will give you many more details. If you have specific questions, please don't hesitate to email us again.