I can only tell you how for a mac computer. On a mac computer you have to press option, and then kind of press all the buttons until you find the right one.
The easiest way, is to drag & drop it from the character map... First, open the document you need the @ sign in then... Click Start. Select All Programs. Select Accessories. Select System tools....
The ticker symbol for Satyam Computers is SAY and it trades on the New York Stock Exchange. It also trades under the ticker symbol SATYAM.BO on the Bombay Stock Exchange in India.