ALSCRIPT produces files in PostScript which may be printed on a PostScript printer (e.g. an Apple LaserWriter). If you don't have a PostScript printer, then you may still be able to use ALSCRIPT if you get hold of the GhostScript software. This is a free package that interprets PostScript commands and can produce output on a large number of different types of printer. GhostScript runs on most hardware types (including PCs) and can also display output to the screen. The package can be obtained from many different sites on the Internet (In the UK try src.doc.ic.ac.uk).
The actual command you need to type to send a PostScript file to the printer will depend on your system. Consult your system manager for help.
Be warned, ALSCRIPT can create extremely large PostScript files if lots of boxing and shading is done on big alignments. On older printers such output may take a long time to process.