You need to become a member of the Club Penguin Team to edit the blog. You can, however post a comment. If your're lucky, Club Penguin will post your comment.
**** Notice *******
When there are alot of comments on the blog the Club Penguin Team will most likely not post your comment :( Did you know during the beta times on Club Penguin Club Penguin could post over 150 comments? Now the limit is less than 70 comments.