At the beginning of your research, it's good to get some background information or an overview of your topic. Encyclopedia and other reference books serve this purpose. You can also use them to find information on a specific event or person. Below are some good reference sources on the Holocaust.
Below are some specialized Holocaust encyclopedias. Some are available online, others only in print.
Below are some examples of articles found in encyclopedias. They are authoritative essays about the Holocaust that could help you expand your knowledge & understanding of the Holocaust or perhaps fill in some blanks in the "big picture" you currently have.