i want to add a marquee to my blog yuvaguide.com
as using atahualpa tell me how to proceed

marque at bar1% in header area

SO just tell me how to embed php on bar1% area in theme

You can't use PHP there. You will need to add a new widget area and then use a PHP aware widget.

As an aside If you are talking about a scrolling marquee I would highly discourage against using one. There are not very user friendly and tend to be quite annoying.