You must acknowledge all sources of information that you use. Pretending that the ideas of others are your own is called plagiarism. The purpose of your reference is to acknowledge the source of information and to enable that source to be found again.
Students undertaking research are expected to list all sources of information in the following ways using APA 6th edition:
Citemaker is an online referencing tool which will help you create correctly formatted references for your assignments. It offers help with print and online resources as well as many others. If you sign up for an account, you can save lists of references. Otherwise just use it as and when you need it and copy and paste the references you make. jAPA is a slightly less complicated version of the Citemaker to help younger students.