There are a few different methods you can use when giving character backstory in your novel. You can add it in the beginning using some sort of introduction like a Preface that will later be important in the story, or you can integrate it. This can be done using dialogue through characters or by using flashbacks where a character is forced to re-live some memories.

If you have any other ways you integrate character backstory feel free to let me know in the comment section below!