The principle behind creating a character map of an existing character is that the reader analyzes the story to find the elements of the character's life, the "backstory" that may or may not be explicitly (directly) told in the story.

For instance, the author or character may state that because s/he is an orphan, s/he was raised by Aunt Willimetta in Nebraska after having been born in Montana. This would be directly told information about the character that would go in a character map.

As another instance, a character may speak crossly to everyone reporting to him at work. The author may never state that the character is obnoxious, but the reader can hear for themselves through the dialogue that the character is obnoxious. This would be indirect information about the character that would go in a character map.

There are specific questions you'll want to answer about the character, in your case, Captain Shure. You'll put each answer in your character map. You'll want to answer who the character is: who the parents are, who raised the character, interests that define her/im, etc. You'll want to ask what are her/is character traits, attitudes, beliefs, and why does s/he have or hold these traits, attitudes or beliefs. You'll want to ask where the character is from: Did s/he grow up in the same place where born? Does s/he work in the same place where raised? Etc. When is usually also important to the story and, therefore, to the characters in the story. You'll want to ask relevant when-questions: born in 1950? working in 1929? Queen in 1560?

You'll want to ask how is s/he involved in the story: the heroine, the best friend, the one in trouble, the one causing the trouble, the one looking on and narrating? Etc. You'll also want to ask if s/he is involved in the solution of the problem/conflict in the story and if so, how? You'll also ask: How does the resolution affect this character? Does s/he go through any character development so that s/he is different in the end or has learned something or has a changed belief or attitude?

A character map is constructed in a couple of ways. You can make a sideways vector map that has multiple branches out to the side from the character name, one for each answer to your questions, or you can make it with branches extending downward from the name. Or you can put the character name in the center and have branches encircling the name, going clockwise or counterclockwise.

Each branch extending from the name connects to a box, circle or space in which you write the briefest possible answer to your questions, bearing in mind that answers may have branches also. For instance, answering Who, you'd write Parents at the end of one branch extending from the name. Then you'd add two more branches to your map extending from Parents, one for mother's name and one father's name. Perhaps the mother dies when the character is eight years old; this would require another branch, which would extend  from mother's name. You'd continue like this, adding branches where and as needed, until all your questions are answered. Bear in mind that character maps are for brief answers.