Since I'm doing a research paper now and i'm not sure if I accidentally plagiarize the contents when i try to paraphrase in my own words, so does anyone know any safe website that has a tool for me to check my essay
The only one I know of is turnitin.com. If they have a trial use, then be sure to use it. Otherwise, they charge a fee.
The other thing you can do is to use Google Advanced:
http://www.google.com/advanced_search?hl=en
Copy and paste phrases or even shorter sentences into the second box ("this exact wording or phrase") and press Enter.
If you are not clear on what plagiarism is and how NOT to plagiarize from a source, read through this entire webpage from Capital Community College in Connecticut:
(Broken Link Removed)
Let us know if you need help with correct citations.