The Oxford English Dictionary defines annotate as "To add notes to, furnish with notes," and bibliography as "A list of the books of a particular author, printer, or country, or of those dealing with any particular theme; the literature of a subject." If you put these two terms together then you have the phrase "annotated bibliography." Which simply means that you are writing notes on a group of sources related to a specific subject.
While you are researching your topic you will compile a list of sources. Once you have your sources, create complete citations for them. After you have read through your sources think about these few questions, as they relate to your research:
Once you have answered those three questions, then you have the entry for your annotated bibliography.