You will find MANY Cold War images online. A word of caution: take care to note where you are getting the image from. Images can be altered or forged, so you should know where it is coming from, who created it, and go to a reputable source. These generally include universities, museums, and research centers. Or, if you find something on a blog or website, note where it came from and try to track down the original image. Below are numerous collections available online. To the left are library image databases that can search through using your keywords; citation information will be provided in these.
IN ADDITION to images, you should also find additional primary sources related to your image. Primary sources were created at the time of an event; so anything produced during the Cold War era that has not yet gone through a secondary analysis. This could include a letter, diary, government document, stock footage, etc. Below are a couple of lists of places to find additional primary sources for your paper.
NOTE: If you are searching for primary sources, the term "cold war" might not work for you - as they might not have been using this term at the time! Rather, searching for specific aspects of the Cold War, followed by a date refinement, might be more helpful.
The following links provide you with images from reputable sources and that are cited/credited.
The following are additional collections, but more work might need to be done to discover where the image came from. This is important to trace so that you know that the image has been unaltered and/or it comes from a reputable source.