Different rules apply if you are using an image as part of a class assignment versus creating something you plan to publish.
For Class: make sure you cite any image you use (see the Citation Guide for format). Most of GCC Library's Databases provide citations in correct format if you find the image in the database. Plagiarism and copyright infringement are not the same. Copyright infringement is illegal and has potentially legal and monetary consequences; plagiarism in academic terms can result in academic consequences (failing grade, referral to administration, academic probation.)
For Publication: Assume all images you find online are copyrighted. Look for an explanation of how the image can be used. The safest designation is one that is in "public domain." These are open for any use. Others may indicate you can use the image with proper attribution, which is the guideline for Creative Commons licenses. When in doubt, contact the creator and ask for permission or don't use!
High quality copyright friendly images, not copyrighted and no restriction for their use. Images explicitly placed in the public domain, no any rights reserved. Public domain images can be used for whatever you want, use it freely for any personal or commercial use.
