Plagiarism is defined as the action or practice of taking someone else's work, idea, etc., and passing it off as one's own in the Oxford English Dictionary. Should you be accused of plagiarism, ignorance of what constitutes plagiarism is not an acceptable defense.
Below are some tutorials that will help you educate yourself and learn to properly acknowledge the resources that you've used.
Read this Chronicle of Higher Education story about plagiarism from a professor's prospective [link works best if accessed while on campus].
UE Honor Code
I understand that any work which I submit for course credit will imply that I have adhered to this Academic Honor Code: I will neither give nor receive unauthorized aid, nor will I tolerate an environment which condones the use of unauthorized aid.