The bottom of each post has a Triangle with a ! inside it. This is for reporting. You must click it on the post that you were treated rudely in.
If it was in chat you have to copy/paste directly from the chat/PM and mail it to a mod. To find out how to mail mods go to the top of the page and click 'Quick Links' ~> 'View Site Leaders'.
If you can't provide a copy/paste or using the report button as proof of your accusation then there is no point in trying to report the user. Also anything said off site is not reportable.
Even if the report is valid, this does not mean you will be notified or made aware if the mods take action.