I started creating web pages in plain HTML. I have a header, main content and a footer. The main content is divided into two, left and right content. Everything is the same on all pages except for the right content. Now I have about 15 pages. This is very tiresome if I make some changes on the other static pages (header, footer and left side content) as I have to go through all pages.
How can I create one HTML file for each static area and how am I going to integrate it?