Everybody knows how to do this by now!!

BUT.. In case you don't here's how...

Copy the Patch file into your Doom II Directory
and enter the following at the command prompt :

DOOM2 -FILE MARKMUS2.WAD

Once Doom II Starts up play the game and get ready
to hear some cool music!  This will NOT alter
your Doom2.WAD, don't worry!

You can also use this patch in conjunction with 
something else, a level for example.
