How to read/validate files from web address folder in c#

I have to read files from web address folder ...so have used below code for that ...i am not getting list of files...

string pathUser = "http:/mentpc.blob.core.windows.net/cents/201503";
string pathDownload = Path.Combine(pathUser, @"20150302110215315197/20150401100536436792");

WebClient client = new WebClient();
Stream stream = client.OpenRead(pathDownload);
StreamReader reader = new StreamReader(stream);

But i am getting exception saying ===>The remote server returned an error: (404) Not Found.

Please help me