Insert date question

Good evening,

I'm script-challenged, and am having a little issue here.

I have a text file that I would like to update fairly regularly, let's call it
Update. Every time I update it, I make a copy of it in the form of
Update_<today's-date>
so that I have a historical record of what shape the file was in every time I
updated it.

I was thinking of making a script to do this, but my scripting is lousy. I
was using emacs (no flames please) to try something along the lines of:

cp Update Update_<code-to-insert-date>
emacs -nw Update

to first make a dated copy, then open up the original for editing.

Maybe this is sheer laziness, maybe it's learning scripting with baby steps.
When I take enough baby steps, I hope to have that "AHA!!!" moment of
comprehension soon.

I've googled, and what looks like might work,
http://list-archive.xemacs.org/xemacs/199906/msg00337.html for example, I
don't know how to implement in emacs, and no flames please, emacs is my
editor of choice (can you tell I'm trying to avoid the "Use VIM!!" comment).
IANAP (i am not a programmer) and like the interface, but there are some
aspects of it that elude me, this being one.

Any help would be appreciated,

Anthony