Redirect Problem

Hi, I have a question about redirecting any page with certain words in
the url. For example, we have many pages that have sitemap.html at the
end of the url, but the actual page we want is site-map.html (notice
the addition of the dash). It would take a long time to add a redirect
to all our pages like this, so we want to redirect any page that ends
in "sitemap.html" to the same exact url except with "site-map.html" at
the end.

Any suggestions?

RedirectMatch looks good, but I'm afraid I'm pretty ignorant when it
comes to server config stuff. I do have access to the server. What
file do I place this in and do I need to include anything? Also, if I
wanted to change any url to the exact same url with a different ending,
what exactly would be the syntax?

For example, www.anyurl.com/sitemap.html
changes to
www.anyurl.com/sitemap2.html

Thanks for your help.