The English Wikiquote does not allow image uploads. However, you can use images uploaded to Wikimedia Commons in the English Wikiquote. The standard image inclusion syntax, [[File:Image name.ext]], will automatically display a Commons image with the specified name. If you want to use pictures which are not in Commons, you can upload them if they comply with the Commons inclusion guidelines, though you will need to create an account there. In addition to images for quote articles, you can upload images for your user pages (like a picture of yourself) if they follow the Commons personal picture guidelines. Note that, to include an image, you will often want to use the following syntax:
[[File:Image name.ext|thumb|Caption or description]].