Professional web developers often create a template of the website layout before working on the content for each page. When you are finished getting the HTML structure and CSS styles to work on your template page, the page can be duplicated for each content page of your site. This process can save you a good deal of time.
Another great time saver is to have separate HTML files for areas that repeat across all or most of your pages. Often the header, footer, and possibly navigation could be kept in separate files. This allows you to make changes in one place that are then applied to every page. Again - this saves you a ton of time going forward if you make any changes.
Read the following document for directions on how to use Jquery to include your HTML header, footer & etc. on your HTML pages:
Web/Programming Languages and Includes with Jquery
