Where did the .mdf file go?

I'm using VS 2012 Pro

I used File>New>Website>ASP.NET Forms Site to create a new web forms website called "Classifieds03".

The connection string in the web.config seems to show that "somewhere" there is an MDF database called:
   aspnet-Classifieds03-20131113091738.mdf

<connectionStrings><add name="DefaultConnection" providerName="System.Data.SqlClient"
     connectionString="Data Source=(LocalDb)\v11.0;
     Initial Catalog=aspnet-Classifieds03-20131113091738;
     Integrated Security=SSPI;
     AttachDBFilename=|DataDirectory|\aspnet-Classifieds03-20131113091738.mdf" /></connectionStrings>

However, what I want to do is to use SQL Server 2012 proper rather than using the mdf file created by Visual Studio.
My intention is to import (attach) the mdf file to SQL Server and then replace the above connection string with one that points to SQL Server 2012.

Now I know how to attach an mdf file to my SQL Server database because I have done it before.

Unfortunately, I can't find the mdf and ldf files.
Please will someone tell me where to find the mdf and ldf files?

Thanks

Ken