Using Creative Commons licensing is a good way to dictate your wishes on how your own intellectual property may be used. It provides some protection in the courts as it provides what amounts to a wrap around license for your material that is agreed to by users of your material.
For example, if you wish to share the history course you teach with the entire world and don't care if people use it, you should provide a Creative Commons license like this. Or, if you have a blog where you want to post your own photographs that you wish to license for income, make that clear by using a creative commons license for each photo like this.
The Creative Commons website explains and helps you create your own licenses and Creative Commons icons.
Note, there is a CC license icon at the bottom of this page.