The APA Style website has many useful hints and tips.
There are quite a few reasons to cite your sources. Your professors want you to:
1 - give credit to authors for ideas and quotations
2 - avoid plagiarism
3 - make your arguments stronger by backing up ideas with other resources
4 - read important material and show you have understood it
5 - let people reading your paper find your sources so they can research further or read what you read
6 - add to the scholarly 'conversation' on a topic by showing different points of view and then delivering your own ideas
7 - learn how to write in a scholarly fashion and how to start doing academic, scholarly research
Citation - information given in a book, index, or catalog which serves to identify a particular title or entry. Citations may include titles, authors or editors, publication data (including dates), volume numbers, page numbers, URLs
Check with your professor what edition of MLA they want you to use.
Game
A citation is how you tell a reader exactly what information you read, referred to, quoted and used for your paper, article, book or web page. Your readers can see what experts you read and which you might not have used. It allows them to read what you have read to see if they agree with your interpretations or to help them further research the same subject.
This is an important part of scholarship and a scholarly conversation. Reading ideas and viewpoints and being able to study where these ideas may have come from and how a person interpreted what they read.
A citation, therefore, must contain enough information to FIND the exact information you used. Depending upon the type of source, this normally includes:
Author(s)
Title of the work
Name of the publisher
Date of publication
What pages you are referring to
Volume/issue for periodicals - edition for books
URL if difficult to find
Type of source
It is much more impressive to your professors to know how much you have read, understood and how well you fit it into your paper than the possibility that you came up with the same idea without reading anything. They want to know that you have researched, read and understood important works on your topics and are starting to be able to include them into your arguments and ideas.
Most of these have citation 'fill in the blank' forms for MLA, APA and Chicago style. Check to make sure you have chosen the correct FORMAT (book, journal, website). Doublecheck your work carefully for errors or use more than one form to see if they match. These are NOT perfect especially with multiple authors.