Need Help with ASP.net

 Hi
 I need help with ASP.NET website, I have received a project from client to update his ASP.net website. I have got Ftp address, have downloaded all the files but the problems is, I can't edit any of the pages, I can only see codes without any design, I have got IIS Server running on my computer as well as I have ASP.net editor(MS Expression). I think the website is been build by using Site builder which is been provided by the Host company on this website. Some of my friends suggested this is built on CMS, but i dont know which CMS system is been used.

I need urgent help with this.
Thank you very much for your help in advance
 
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