NtEd assumes that:

lpr <file>.ps

prints a PostScript file named <file>.ps on your system. If this isn't the case then configure the printing command. Choose:

Edit → Preferences → Configure Print ...

On dialog textfield you should see:

lpr %s

The %s will be replaced by the name of a PostScript file. Change this string according to your needs. For instance: If you want to use the kprinter from KDE then change the string to:

kprinter %s

and press OK!

If all is configured then choose:

File → Print

You can export the score as PostScript. Choose:

File → Export PS...

Select a file name on dialog and press OK.

Because most printers are able to print PostScript files you can print this file using your preferred printing command (lpr, kprinter, ...)

You can export the score as PDF. Choose:

File → Export PDF...

Select a file name on dialog and press OK.

Because many printers are able to print PDF files you can print this file using your preferred printing command (lpr, kprinter, ...)

You can export the score as MIDI data. Choose:

File → Export MIDI...

Select a file name on dialog and press OK.

If the score contains lyrics NtEd exports them to MIDI. This causes many midi players among them kmid to show a Karaoke-like behaviour:

You can import a MusicXML file. Choose:

File → Import MusicXML...

Select a file name on dialog and press OK.