There are a lot of contests and trainings on Codeforces now. And it's difficult to find a tutorial or announcement for a specific contest.
And now you have an opportunity to attach materials (Codeforces blogs or external URLs) to any contest. You can click on the paperclip below blog's title and fill the popup form to attach blog entry to the contest. Or you can attach any URL in the contest's sidebar frame. There you can see resources that are already attached to the contest. Visibility of material depends on user's locale and current phase of the contest. For example you can't view statements before contest start.
The access to manage (add or delete) resources of the contest have administrators, contest managers and all "red" users.