Adding commentary in the form of occasional blog-type posts add value to your curated content by providing an editorial focus for your curated list. Commentary can come in the form of a response to one of the articles, a post that ties seemingly unrelated curated pieces together, or original research on the topic.
If you are uncomfortable writing original content or need extra practice, then check out the P2PU challenge Writing for the Web.
Most curation tools include features that let you write a post of original content, however, you could always write it as a Wordpress or Tumblr post and then curate it like any other post.
Paula at Curating Content for Online Education has suggested adding value to your curated content by critiquing the original post, contextualizing the original information by relating it to other posts, and expanding the idea of the original post by using it as a "jumping off" point to continue a conversation.
Write your first post as a statement of purpose and share it below.
example of a short statement of purpose: This site will curate content related to First Amendment Establishment Clause cases appearing before the Supreme Court of the United States. The Establishment Clause of the First Amendment to the Constitution states, "Congress shall make no law respecting an establishment of religion." Over time, the Supreme Court's interpretation of the clause has changed. In addition to current news stories, original court documents from Westlaw and historic legal journals will also be explored