All novels have to have some essential features. Most notable is a structure that usually follows a pyramid form and includes other elements -- I have bolded the most common elements of fiction.
1. Exposition is the initial introduction to the main character(s), setting, and other background information. Sometimes the basis of the conflict is also established.
2. Rising Action/Complication is when the characters meet their conflict issue. A novel must have some sort of conflict in order to be 'interesting' and in order to develop a theme -- another essential element of a novel. Conflicts can be one or a combination of the following: man vs. man, man vs. himself, man vs. environment, man vs. nature. Theme is another word for meaning and it is for meaning that we read. What truth of life is the author trying to illuminate in this novel? What lesson could we take away? Conflicts create themes, so if you are ever wondering about theme, define the conflicts first and then draw a conclusion from there.
3. Climax is the point of the novel when the main characters have taken actions or made choices and created a new situation where they cannot return to the way things were before that act or decision. Climaxes aren't always the most interesting point of the story, and they don't always happen in the middle of the novel.
4. Falling action is the aftermath of the climatic moment.
5. Resolution is the conclusion of the novel. It is here that the ultimate point an author is trying to make is established and the reader can tie together subplots, sub-themes, minor characters, etc.
Novels use multiple methods of characterization such as the way characters, act, speak, think, and what others say about them. Novels must have a narrator -- a first person narrator is a character telling the story; third person narrators are outside the story and can be all knowing, or only present a limited knowledge of one character's thoughts and motives. Novels sometimes have symbols or motifs that run through them -- these are real things that also have suggested meaning and those meanings usually connect to the themes of the novel. There are obviously lots of other devices that are common in novels. The web sites below could provide other ideas.