You are free to read all messages, but to post a message you need first to register (or login, if upon registering you didn't tell the system to remember you). Registration is quick and easy, it is done only once (the system will recognise you in the future if you select so), you are not obliged to give any personal information at all, not even your e-mail address (although this will be useful if you wish to be notified when someone answers one of your posts or if you lose your password), you will be able to edit your profile and your old messages in the future whenever you want...