If you use an image you did not create, you must provide a citation. Image citations can be formatted according to the citation style you are using.
Image citations should include the following information:
If you found the image in a book, you will also need the author, title, publisher information, date, page, and figure or plate number of the reproduction. If you found the image online, you will need an access date, the web site address (URL), and, in some cases, an image ID number.
It's important when you look for material to put in your project that you consider the copyright status of that work. Even if something is freely shared on the internet, it doesn't mean that content can be copied and shared freely without violating copyright. There are two kinds of works you should focus on in your searching that allow for straightforward reuse:
See the Understanding Copyright tab to learn more about Creative Commons and public domain.