An Annotated Bibliography is a collection of resources that you have used or plan to use for your research. Instead of simply listing the sources, an annotated bibliography requires you to summarize and assess the sources you have chosen.
Annotated Bibliography entries generally consist of two parts.
-First is the citation, which in your case will be in APA format.
-Second is the annotation itself (summary and assessment of source).
Note that an annotation generally consists of a summary of the source, an assessment of the source, as well as its relevancy to your proposed topic. Annotated Bibliography entries can vary from 1-3 paragraphs depending on your assignment guidelines.
The Purdue Owl's APA format page shows how to format the title page and abstract.
The Purdue Owl's sample entry will show you how to format your entries. Be sure to scroll down, APA style is the second example.
The University of Toronto's webpage on writing Annotated Bibliographies, it takes you through the whole process starting with how to select your sources.
Cornell University provides more things to consider when writing an annotated bibliography.