Start by finding out the basics about your topic and it's context within the field of social work and social policy.
Encyclopedias and reference books (e.g. handbooks, dictionaries, etc.) are a starting point to gather knowledge on a topic that is new to you. They can be a used to supplement your textbook readings and will help you understand how your topic fits into a broader context. Importantly, encyclopedia articles identify the major works on a topic and introduce terminology that you can use as search terms as you continue on with your research.