If you don’t understand rules of quotation, citation etc., it is possible to plagiarize someone else’s work without knowing that you are doing it.
If you are still unsure about what constitutes plagiarism, visit Plagiarism 101. It is a great guide!
Zotero collects all your research in a single, searchable interface. It is very easy to use and, with the upgrade to Zotero 5.0 for Windows in July 2017 the download and install is more straightforward. Video tutorial material for the new Windows version plus new tutorials on the Mac version of Zotero will be added to this guide as it is available in the meantime, these resources may be useful: