Here are some useful links explaining how to write an Annotated Bibliography.
An annotated bibliography provides a brief account of the available research on a given topic. It is a list of research sources that includes concise descriptions and evaluations of each source.
The annotation usually contains a brief summary of content and a short analysis or evaluation. Depending on your assignment you may be asked to reflect, summarize, critique, evaluate, or analyze the source. While an annotation can be as brief as one sentence, the standard annotated bibliography consists of a citation followed by a short paragraph.