In dreamweaver there is a meta tag ,keyword area do I enter required information page by page or once I enter thois once it will be enough for the whole website ?
You should download wordpress instead , you'll have a whole lot more success. As for the "dreamweaver" question. No there is no option for that, You will have to hand code the meta tags into each page manually if you are creating HTML pages.
each page will have unique meta tags, title , keywords and it is not just good for seo but suppose if u hve 10 page websites then u will enter meta tags for each page manually.
Curious how you know that. He/she hasn't even stated what kind of site they are building. obviously I love Wordpress but its false to think it can create anything.
there are many sites out there that will create meta tags for you, i think www.webmaster-toolkit.com is one of them. You could use those to get you started