how to Modify HTML document and redisplay?

Hello all,
I want to create one application which keeps track of the IE running. when any new url is navigates.., it find in the database that the particular url is in database. if yes then the application should modify the back color, background image and font etc.. Currently what i think to use is Parse the WebPage in HTML and Modify the tag value of backcolor and font .. and then display the page again.. Dont know how to do this?? if any body have any idea plz let me know.
[498 byte] By [try.test.abc] at [2007-11-20 10:40:56]