Zaxo got it in one. Use a templating system. HTML::Template is one i've used extensively before, however others prefer other templating solutions.

Build your html page as if it were a static page (ie it works) then slurp it up and spit it out with your templating system of choice.

After you've got that down pat, its not too much of a leap to include your own content, or personalisation, (Welcome <user>)