To block someone in the forums, click on "control Panel" towards the upper left of this screen, in the menu that comes up on the left side of the screen click on "edit ignore list" and add their name.
To report someone it depends on the scenario. If its something in a forum post, click on the "RAP" button in the upper right corner of the post. It notifies staff to look at it automatically. If it's in chat you can either talk to a that is in chat at the time, or CC mail myself or any other moderator with the complaint, preferably with some evidence of the issue such as copied text.