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.
To make your story workable it will have to be on the logical side. Your story will have to have rules, limitations, and even structure. You should be prepared to explain how it works, or why the things in the story may happen. If you are going to write about supernatural creatures such as werewolves, and vampires they will need limitations. Magical and fairytale beings in your story will need to be explained as well.
You will need to make an outline before you start writing. All an outline is, is just your idea put down on paper. The main character, location, and the main points in the story will need to be included in your outline. Make sure to write down any and all details for your fantasy world.
Next you will need to decide on your main character. In making your character there are many things to consider. You will need to decide the gender. I find it easier to write a character that is the same sex as myself but some plots may call for the opposite sex. Then you will need to decide on age, occupation, and background.
The main character can be the hardest one in your book to make up because you have to make a whole person from scratch. You need to describe the characters physical traits and personality to your readers. When describing the physical traits you will need to add things like height, weight, hair and eye color. Gradually implement this traits into your story. You do not want it to read like a list.
Next the main character will need a personality. Describe the personality to the readers so they will know why the character is acting or reacting to a situation the way they are. Make sure to add descriptions of the personality such as shy, quite, outgoing, arrogant, dumb, sassy, or loud.