Creative Commons has an extensive wiki entry on how to apply CC Licenses to various types of works. Including links to examples of how to insert the code into your blog or website, and advice for online and offline documents. 

The Creative Commons  License Chooser is a fast and easy to use tool that allows one to both evaluate which license is best for your use, or if you already know which license you with to apply to get the appropriate Icon, HTML or XMP code to make license machine readable and easy to display on websites.  

Many services that host creative content, such as YouTube, flickr, Vimeo, Wikipedia to name just a few allow users to select a creative commons license for their works. 

For example when uploading a video to YouTube it will automatically apply the Standard YouTube licence. If you are logged into your account, you can change this by clicking on the ‘Edit Video’ button underneath your video and then clicking on the ‘Advanced’ tab. Click on the dropdown box ‘License and rights ownership’ and select the ‘Creative Commons – Attribution’ option. This will then mark your content as CC BY.

Insert a copy of the appropriate CC icon from: http://creativecommons.org/about/downloads

Add some text, e.g.: “This work is licensed under a Creative Commons Attribution 4.0 International License”

Insert a hyperlink from your licensing text  to the appropriate license.