You have to select a Segment in a Segmentation drop-down menu (at the top left corner of the page).
or Create New Segment

Content Segmentation

Segment your posts and compare different segments to find out which type of content is the most engaging for your followers. Are retweets less engaging than your own content? Are posts of a particular topic more effective than others? Was your social media campaign more successful than your usual content, and by how much?