This facility is not available this time in web version,but if you want sends message to admin than you can follow these process

Open> Put your nick name and password than submit it (you will enter in chat)-> Now you will see 3 options "Rooms", "Menu" and "Users" -> Select "Users" ->Here you will get 8 options, press left mouse button on "Moderators" than dragand drop it in right or left panel -> Here you will get a nickAdministrator, than click left mouse button on Administrator -> You willagain get some options -> Select "Private message" -> Now you can sendprivate message to admin.