Instead of hard-coding these in the .cs code, you could use the following:
string inputFile = ConfigurationManager.AppSettings.Get("FileLoc");
In the web.config, in the appSettings section, enter something like:
LSBadd key="FileLoc" value="C:\somewhere\File.xml" /RSB
LSB = Left square bracket
RSB = Right square bracket
You can also do this from Visual Studio when viewing an .aspx page. Click Website / ASP.NET configuration and type in the entries there.