There are great deal of images on the internet - and it's overwhelming! Before you start your search, think about:
When using an image, do your due diligence to find its source so you can properly credit the maker in your work. This may entail some sleuthing if the image you found is on social media or reposted from somewhere else on a website.
Instead of first turning to Google Images, here are some good places to start your search:
James H. Karales. Martin Luther King, Jr. 1962. Retrieved from the Digital Public Library of America, https://idn.duke.edu/ark:/87924/r4g15tm0n. (Accessed April 29, 2022.)