When adding images to your schoolwork it is important that you:
only use pictures that the owner is happy for you to use
always include details of where you got the picture from.
This libguide includes details of websites where you can find pictures to use in your work.
This video will give you a clear introduction to copyright and creative commons:
Creative Commons (CC) is a global non-profit organisation that enables sharing and reuse of creativity and knowledge through the provision of free legal tools.
CC licences are not an alternative to copyright. In fact, they apply existing copyright law.
Users of CC licensed material are permitted to use the material without the need to further seek explicit permission from the owner, so long as the use conforms to the licence attributes.
There are a number of sources of CC resources, including images, which can be used in your work. This often means they can be used without seeking permission from the original owner but you must still cite and reference each item in your work.
This site offers a convenient way to search a number of sites which include Creative Commons images. Do not assume that all the search results are under a Creative Commons license - when you have found an image you should check it's licence before using it.
Pixabay is a repository of high quality images that you are free to use in any way you like.