There's a couple of ways. One way you can do it, is click on the name of the poster, view their public profile and there is an option on the top of that page to add them to your ignore list.
Go into your User CP and click on the Buddy/Ignore Lists link at the bottom left hand section...then add Fred's name to the appropriate spot. It would be much easier if you could just add "Idiots who post mindless drivel", but alas there is no such option.
