You have subscription access through our web site to the online version of The Chicago Manual of Style. You can search or browse either the 17th or 16th edition. In each edition, Chapter 14 deals in detail with citing your sources with notes and bibliography.
Print copies of the Chicago Manual and of A Manual for Writers of Term Papers, Theses, and Dissertations by Kate Turabian, which presents the same citation styles (very slightly simplified), are available at the Research & Access Desk.
The Chicago Manual (and therefore the Turabian) offers two systems of citation. For history classes, you'll use the one with Notes and Bibliography system. (The other system uses parenthetical author-date references and a corresponding reference list; you can ignore it in history classes.)
When you look at the "Notes and Bibliography" tab of the Chicago-Style Citation Quick Guide, each example of a note begins with a number. Every example without a number is a bibliography entry.