Any of the blue names, or if it is in regard to a particular post, in the bottom left corner of the border around the post is a little triangle with an exclamation mark in it.
That is the 'Report Post' button.
Report what you think is wrong with the post, and we can have a look at it.
These things don't happen instantaneously though, so bear with us.
Click on any blue name and a drop down menu will appear. One of the options is to send a pm (personal message). Click on that and a message window will pop up. Type and send your message. Like Rory said...its not instantanious. We all have lives and day jobs, so be patient with us. Lol. Most of us try to sign on several times a day and most things get dealt with fairly quickly.