When using photos or other images from the web, you want to be careful. Just because you find it on the Internet doesn't mean you can use it freely. Creative Commons Licensing is one possibility for finding useable images, but even CC licensing varies. Be safe and read the license agreements. Choose the least restrictive license options, either CC0 (public domain) or Attribution CC BY. https://creativecommons.org/licenses/
Just like citations for written works, it is important that you provide citations for images you use that are not your own. If you don't you are taking credit for the image as your own work. However, adding a full citation to your image within your work may be cumbersome. It is acceptable to use an abbreviated “in-text” style attribution (Title, Author, CC0 2.0) with full attribution at the end in a works cited list. In a presentation this may be a slide at the end. Image citation should include the following elements:
T = title of the image
A = author or artist
S = source
L = license for the image, including a link back to the source page with the license
Instead of grabbing images from the web, make your own images. If you create your own images, you know that they are safe to use!
Draw, paint, create “claymation” images...
Use a digital tool -- Canva, MS Paint, Google Drawings, Adobe Spark, Piktochart, Sketchpad…
Take your own photos. (You don’t need permission from the person if they are not recognizable or if the photo is at a public event and used for journalistic purposes. Otherwise, you can use a simple “photo release form” and have the subject sign off use rights. School districts cover this for you for school-related events.) Images that contain logos or stores require permission of the company for publication use.
You can protect your own work by marking them with a Creative Commons License specifying how others can and cannot use your work.