How to get file modification history in file

I am an 'old guy', and have used several source control systems for a few 
decades.  I am now trying to use CVS as a n00b, and am struggling with some 
basic concepts.  I have RTFM'd and lurked here for a while, but I can't 
figure out how to get the modification history for file changes to show up 
at the top (or bottom) of a file.  The docs are somewhat vague on this, but 
I think I see something related to keyword substitution.  Could somebody 
please explain the strategy on how to do this?  Context of *.cpp and *.h 
files should get me going.

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