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1. Place the cets_blogtopics.php file and the cets_blog_topics folder in the wp-content/mu-plugins folder.
2. If desired, place the widget files (located in the widgets subdirectory) in the wp-content/mu-plugins or the plugins folder. It's recommended that you use the plugins folder and only enable these widgets on blogs that need them. They may be confusing for some users.
3. Go to Site Admin -> Blog Topics Management to add/edit topics. You should enter a name and slug for each topic you wish to use. Description is optional. It is used in the BT Topic Name widget and in the example theme code.
4. Blog admins can go to Settings -> Blog Topic to edit their assigned topic.

If Use of the Portal Aspects are desired

1. By default, none of the widgets use the portal links. If you want to use the portal links, examine the sample theme. The most relevant bits of code are in rewrites.php, topics.php, and sites.php. The portal code rewrites links such as ?topic_id=1 to /topic/slug.