Plagiarism is a very serious offense both in academic and professional world.
In order to avoid plagiarism, give credit whenever you use any type of information that others have created. The crediting consist of citations that connect the borrowed information to the original source of the information.
There are many citations styles in use, depending on the discipline or journal to publish your research. For your college papers, it is recommended to use the citation style recommended by your instructor. If there is no required style, pick one you are most familiar with and be consistent.