You will need several things to get started when you write fantasy novels. You should have an idea first of all. This can be a little harder than you might think. You want it to be workable. But if you want people to read your story it should be interesting as well.
By workable I mean that it needs to fit into some type of logic. You will need rules, structure, and limitations. Be prepared to explain the whys and hows. For instance if you write about ghost, vampires, or werewolves then you will need to explain what limitations they have. If your writing about magic, or fantasy creatures you need to give some idea of how this works in your fantasy world.
The next step to writing your novel is to make an outline. An outline is basically just putting your plot and characters down on paper. You want to be sure to include your main characters, the location the story will take place, any main points to your story. When building your fantasy world you want to think of all the details you will need to make your world and write them down for later use.
The main character of your story will need to be decided. When deciding on a protagonist (main character) you have to pick a gender. Some people would rather write a character of the same sex they are. That may not always work if your story line calls for the opposite gender. Next is the age, occupation, and background of your protagonist.
I find that the leading character is the hardest character in the book to make up because you will need to know the most about this character. Make sure to include the characters physical traits and personality. Height, weight, hair and eye color are just some of the physical traits you will need to describe to your readers. Make sure these things do not read like a list, you need to gradually add the traits into the story line.
You will need to establish a personality for you main character. Is the character shy, quite, outgoing, loud, arrogant, sensitive, smart, friendly, or even mean or evil. Your characters personality will determine their actions and reactions later in the story.