The characters in your novel are just as important as the stuff that happens to them. You (and your readers) are going to be spending a lot of time with them, so it's important to make them worth reading about. Note that they do not have to be likeable, but they do have to be interesting, and there should be a reason that they are in your novel.
This post will take you through a method of creating characters that will be relevant to your novel, interesting to you and that have their own voice. It is likely that this voice will change and develop as you keep writing your novel, but this post is designed to give you a jumping-off point. As you go through the process, make note of anything you need to research later so you don't get distracted.