You'll find information on the possible consequences of plagiarism under the section on Academic Integrity & Academic Honesty.
The short videos on this page from Rutgers University Libraries are funny, but very informative. If you have any question about when you need to cite sources, please watch them!
Purdue's Online Writing Lab (OWL) is one of the best and most reliable online style & formatting guides.
There are many helpful style & formatting guides online but you may still have to consult the official handbook in some cases.
A word of warning: These sites FREQUENTLY create citations that contain errors. Still, some students find them easier than creating their own citations. If you use these, double check their work very carefully.
Printed versions of these guides are available by the Research Help Desk on the main floor of the Library.
These videos have really great content (even if the production value isn't that awesome).