Glad you ask!
Here are our tips to find an image from the scene you are looking for in order to create a spot or wanted:
You can start with a Google Image search. Look for a character or an actor, a movie, an episode or a season. You might find what you're looking for a lot easier than you thought !
You can also visit screencaps websites. Thoses websites reference thousands of screenshots of movies and series. Here a list of a few of them :