Modifying existing Web Site

Question

hi everybody i have a web site say "www.anwa.com",this site is published on the internet but it is incomplete,so i need to change some pages and add new ones with database support "xml....".The site has been build using ASP.NET 2.0 So my question is how can get started with that ....with simple steps.... My second question is "how can i build the new pages with the same appearance with the old pages ?,i.e can i get the Master page from the web ?"... plz i need help because this is an urgent case......... thanks