My NCBI is a personalized account which allows you to save search, set preferences, etc in PubMed and other NCBI resources. For help with these features, please contact your librarian or see the help manual.
This book is an overview rather than a help manual. "Each chapter is devoted to one service; after a brief overview on using the resource, there is an account of how the resource works, including topics such as how data are included in a database, database design, query processing, and how the different resources relate to each other."