Most research questions arise from what is already known--whether by you personally or by the researchers and scholars in your field. In your early years as an historian you will need to rely on background sources to get a measure of what appears to be the accepted knowledge on your topic. Your job is to add to that knowledge.
Also, in making and revising search statements, and in making sense of search results, you will need to become familiar with the names of people and places, dates, and concepts related to your topic and your question. In many cases you will also need to know the variants in the names and spellings.
You can use these sources to get started on your research or to help solve problems you face later in your research.