"diff files": how to use?

[John Gordon]

	Hi, everyone.  I apologize if this is a simple question.  I have
several "diff files" and I don't know how they are used.  I did a man
on "diff" and read the FAQ, but neither seemed to help.  Thanks for any
help.  A sample of my diff file is appended.

---
John Gordon
Internet: gordon at osiris.cso.uiuc.edu        #include <disclaimer.h>
          gordon at cerl.cecer.army.mil       #include <clever_saying.h>

-----
*** Makefile.dist	Mon Jan 14 11:15:38 1991
--- Makefile	Thu Feb 28 13:08:51 1991
***************
*** 8,13 ****
--- 8,17 ----
  
  CFLAGS = -g
  
+ BINDIR = /usr/local/games
+ # this must match "GAME_HOME" in files.h
+ LIBDIR = /usr/local/games/lib/mdg
+ 
  DOBJSA = dmain.o seg.o monsters.o msghandler.o findplayer.o godpower.o
  DOBJSB = players.o random.o combat.o effect.o ranged.o speak.o dmsg.o
  DOBJSC = spells.o improve.o dident.o magic.o traps.o loadconfig.o
***************
*** 47,51 ****
--- 51,66 ----
  	
  ident : $(IOBJS)
  	cc $(CFLAGS) -o ident $(IOBJS)
+ 
+ install: $(PROGS)
+ 	strip $(PROGS)
+ 	cp mdg_char mdg_daemon mdg_stop mdg $(BINDIR)
+ 	ln $(BINDIR)/mdg_stop $(BINDIR)/mdg_save
+ 	-mkdir $(LIBDIR)
+ 	-mkdir $(LIBDIR)/bin
+ 	-mkdir $(LIBDIR)/players
+ 	cp ident mdg_clock $(LIBDIR)/bin
+ 	cp mdg_dir/default $(LIBDIR)/players
+ 	cp mdg_dir/item.start mdg_dir/map.start mdg_dir/monster.start mdg_dir/note.start $(LIBDIR)
  
  # end of Makefile.