Are you still looking at the Demo, because there are restrictions on it to keep it from being fully operational?
When you click on the "Open Input File" button it opens a file retrieval window. If you look in the manual at the page about this there is a very clear picture showing setting up for the File Type. For Karaoke
(*.bin, *.cdg, *.mp3+g, *.zip) and for Audio
(*.wav, *.mp3, *.wma).
If this isn't what you are seeing, you don't have the full version.