Citations are a critical part of your paper. Without them, no one reading your paper would know what research you conducted, which articles/scholars you are referencing, and where many of the ideas came from. You also risk being accused of plagiarism if you don't cite/attribute the ideas or actual works of others.
Citations are useful too. They allow readers to reference additional material about your paper. Citations place your paper in the context of a bigger set of ideas.
Citations are in the text (the actual place you use someone else's language or ideas) as well as at the end of your paper. The in-text citations are brief. Usually, no more than a last name and date in parentheses within the text of your article like this (Germano, 2009). Citations are more complex at the end of a paper since they reference the full article, book, or web page. References listed at the end of the page look like this Germano, Michael (2009). 'Citing Articles Doesn't Have to be Hard,' The Journal of Research Can be Easy, 1(2): 2-5. The citation is a complete 'address' of where to find the article.
There are lots of tools to help you cite in text and for a list of references. These include Refworks, Library Workshops, and help from the reference desk.