I am running this site haircareresources (dot) com. All these pages are static htm pages. Is there any way to manage left navigation just like include files so that i dont have modify each one of them ???
Wrong, there's a thing called server side include that's used in html http://www.boutell.com/newfaq/creating/include.html
yes you can do that with html, or you can use frame or javascript function to call other page but recomended to use any programming language, if you can't create by your self, better than you use instan CMS, its powerfull and easy to maintain.
You can read about (and learn how to use) server side includes and PHP includes here: http://forums.digitalpoint.com/showthread.php?p=2145250#post2145250
As your site is on IIS6 servers it would be easiest to just use ASP.Net's master files. Create a template, add a content control. All pages then simply have the content and IIS automatically puts the content into the area you have the content control