Flickr has millions of CC images that you can use (with attribution). Simply filter your search results by license type. Use the 'Share' option to embed images with proper CC attribution.
ImageCodr works best for inserting byline & license information into a website or blog. Paste the URL of a Flickr image to generate the HTML for the license information.
Self-paced tutorial to learn how to document information, check citation examples and learn about copyright, intellectual property and how the internet shapes information use.