The simplest way to display lyrics in Winamp is with the help of a plug-in. Luckily, there are plenty available for this purpose. I recommend installing Lyrics Plugin from the following page: http://www.lyricsplugin.com/
Download the version for Winamp and install it. Make sure the Winamp is installed and turned off. The Lyrics Plug-in will automatically identify the song you're playing and display the right lyrics.