You should see a menu on the right side of this page on which you are able to register. Once you do, you will be a subscriber. If you cannot see it, try here.
Contact any of the administrators if you need access to write on the blog, in which case you may become a contributor or editor.
To enable profile pictures, well, wordpress works in a different way. It turns out you do not have an avatar picture on this site but on some 3rd party site which will keep that avatar for every wordpress site you use.
You may go to: Gravatar and do that, it’s rather simple.