Citing your sources is an important part of writing. It allows you to give proper attribution to the authors on which you are basing your work and allows your readers to trace back from your work to the original sources.
You have been asked to use Annals of Pharmacotherapy for your PHAR509 projects. You could do this manually as you are writing the document; however there are a number of tools that are available make writing and citing a less time-consuming process. I have listed a few options below and I'm happy to talk with you or your group to learn more about them if need be.