How do I add warning "turn on wifi"?

Hello, i have highscore in my game, it is on online database(global highscore), how do i add warning to "turn on wifi for submit your score"? I want to prevent players thinking that the highscore is broken.

That warning should be active only when the device is not connected to internet connection.

Thank you.

http://stackoverflow.com/questions/4282 ... javascript

Then based on the reply, display message.