|Step one: Login to Movable Type
You'll want to start by logging into your Movable Type installation, and finding the "Edit Configuration" link for the blog you'd like to license.
Blog setting screen before license selection (explanation links to http://www.sixapart.com/movabletype/docs/3.3/help/blog_settings_general/creative_commons_license.html):
Clicking launches the CC license chooser in a popup:
After choosing a license the popup closes and the license chosen is shown in the blog settings screen: