title: How can I choose startup object in Visual Studio?
body: <p>There are three cpp files and if I start debug, an error message appears: "Choose startup object."</p>
  
  <p>So I clicked 'Current document' but nothing has changed.</p>
  
  <p>Some peoply say do right click on solution and go to 'properties', but I can't find the 'properties' menu...
  How can I choose startup object?</p>