Always give credit. Always indicate where sources of information in your paper came from. Giving credit to the source is what is meant by citing the source of information.
In research papers, the format you use to cite your sources will generally be determined by the style your instructor asks you to use. Read instructions carefully and follow them. If you're not sure, ask your instructor. Use the contact information on your course syllabus to call or e-mail your instructor for further clarification on the assignment.