1.In your "Web Site Project" you should add a folder named "MyFiles" for example, by using Visual Studio;
2.Move your .txt file into this folder;
3.In Visual Studio select this file to be part of the project, then select the file and in the Property window, set up the "Build Action" property with value "Content" and the property "Copy to Output" should be "Not Copy";
3.In Web.Config add the next lines inside the "configuration" section:
<allow users="*" />
This will allow the access to this folder at runtime.