Personalizing & Adding New Content To HTML Emails.

I need to create a module where a technical novice can send an email newsletter (that has already been created and uploaded on a server) to a list of subscribers.

I know this can be done using CDO.Message and CreateMHTMLBody

My question is how can I add a few lines of new content like say a header and footer and may be some personalization (like a direct unsubscribe link for each subscriber.) to an already existing html file before emailing it out.