Note that the author of this guide is not an attorney and is providing information on copyright only. Nothing on this site should be taken as legal advice. For legal advice, please see an attorney.
Images are generally copyrighted as are literary works. Anything created before 1923 is out of copyright and in the Public Domain and can therefore be used as desired.
To find images you can use, look at the Resources tab for sources of copyright free images.
Some textbooks give instructors access to electronic files including the pictures in their books. These files are usually intended to be used in things like PowerPoints. You should be cautious about putting such a PowerPoint on the open web for anyone to see but secure websites like D2L where only students registered for your course can see the PowerPoint probably offers little threat. You should check the license agreements that come with electronic files associated with a textbook to find out how you can use images within those files. If you want to scan an image from your textbook, look at the instructor information in the textbook or contact the publisher to see what their policy is.
One type of image that is not copyrighted is a photo of another work of art unless the photo is made in such a way that it is original in itself. For instance, the photos I took at Musée L'Orangerie in Paris of Impressionist paintings are not copyrighted as they do not present any orignality themselves. However, if I were to take one of my photos and manipulate it to show the painting in a unique way by overlaying a transparent color and adding a fancy frame within the photo, the photo would be covered by copyright.
Use this form to search for images that are licensed for reuse with creative commons licenses. Please be aware that not everything this search comes up with will have a creative commons license so please check for the license graphic or text before you use an image. There are a number of search engines you can use with this form - the "Search using" box allows you to choose what search engine you will use.
Briggs Library provides access to two art databases which can provide images for educational uses. Be sure to properly cite the images as the databases require.
Permissions by 
This image indicates that the work must be attributed to the creator.
This image indicates that the work must be attributed to the creator and no derivitive works can be made from it.
This image indicates that the work must be attributed to the creator, the work cannot be used commercially and any derivitives created must be shared with the same license.
This image indicates that the work must be attributed to the creator and, if you make changes, you must share it with the same license.
This image indicates that the work must be attributed to the creator and it cannot be used commercially.
This image indicates taht the work must be attributed to the creator, it cannot be used commerically, and no derivitive works can be made from it.
