These links will help you quickly understand the issues around copying, paraphrasing, editing, plagiarism and correct citation.
All My Own Work - a comprehensive, easy to access guide to acknowledging sources, plagiarism and copyright.This site is from the NSW Board of Secondary Studies and will be compulsory for all NSW high school students from 2009. It has almost everything you need to know - simple!
The Plagiarism Test, University of Michigan - a simple 4 question quiz which shows you exactly the difference between copying, paraphrasing (moving the words around) and creating your own scholarly interpretation.
University of NSW - an easy "Problem and Solution" approach to avoiding plagiarism.