You can only give reactions by sending an email. It is not possible to create an account and react directly on the blog. The reason for this is simple: it is the purpose of this system to stay as uncomplicated as possible. The creation of accounts, logging in, keeping track of sessions, constantly keeping an eye on reactions makes the system more complex and to work with. That is not the aim of the system.
Therefore: if you would like to react, please send an email to blog (mail address has to be implemented yet, my apologies). If you add the domainname to that address, then will your email arrive in the proper emailbox. If the content and the language is deemed appropriate, then will your reaction get added to the blog.
Please tell where you are reacting on. If you react on an earlier response, do tell, as I will try to insert your reaction at the proper place.