MS build Programatically

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C#

ASP.NET

C#4.0

Can any one help me in building a web application using ms build programmatically step by step using C#.net but not through command line.
I am breaking my head seeing different posts on MSbuild but no one explained it clearly.I have done a sample using the below code, it is working only for .csproj kind of extension but not for .sln extension.

var project = projectCollection.LoadProject(solution_name);
          var fileLogger = new FileLogger();
          fileLogger.Parameters = @"logfile=" + logfile;
          projectCollection.RegisterLogger(fileLogger);

          bool result = project.Build();
          projectCollection.UnregisterAllLoggers();
          return result.ToString();</pre>

For .sln it is throwing an error as below
The project file could not be loaded. Data at the root level is invalid. Line 2, position 1.

Please let me know the solution for this and I will be thankful to them.