- Who the creator is
- What CC license the material was made available under
- Where the source material can be located.
The Creative Commons homepage provides detailed information on how to give appropriate attribution to content creators in your own web content, in web, video, photographic and audio materials, as well as standardized markers and attribution templates that you are free to download and use yourself:
For example, I use the video bumpers provided by CC in my videos, and the CC official markers in other web materials. It's dead easy, so take a look.
If you have further questions, be sure to check out the detailed FAQ at Creative Commons: