For the most part, image copyright is no different than the copyright of anything else and these copyright principles still appy.
Like most uses of materials for the purpose of education, we are often able to apply Fair Use. Fair Use is an allowance for the use of copyrighted material, which is based on a set of criteria to be considered when determining whether your use of an image or work is infact fair. Those 4 principles are:
Whether the use of a work does indeed fall into the category of Fair Use is subjective. Instead of offering hard and fast rules, think of Fair Use as a set of guidelines that should be followed. For more specific details, read up on Fair Use through the U.S. Copyright Office.
Use of Images & Licenses
To apply your own Creative Commons License, which means accomodating for limited use of rights, you can go to Creative Commons.
Citing images is like citing anything and you should include:
Sometimes you don't get all that information, or no one knows who the artist was. In these cases, you leave this information omitted.
These websites are tools to help you correctly format an image citation.