You can tag by writing @ username without the space. But do use a space after the usename, so no point or comma or so directly after it!
If there are two names, the username is the one between brackets, if there is only one, then that is the username.
There is no need to tag me, as I read all the posts and check them several times a day, but you can of course. My normal username is spikeyxxx. I’m on a special (admin) account at the moment and it only displays my real name, but spikeyxxx still works. Maybe Martin Bergwerf will be @taggable as well…?