Plagiarism, in the academic world, is using someone else's ideas or research and not indicating in your paper that are using these ideas. Even if you put someone else's research into your own words, if you don't provide proper indication that you are using someone else's research, it's still plagiarism. You are expected to use other people's research in writing your paper, but you need to provide references to this other research in your paper. For your paper, you'll be using APA style. See the APA page for more details on how to do this.