title: how to check if item is selected from a comboBox in C#
body: <p>I'm pretty new here.</p>
  
  <p>I have a form, and want to check if the user filled it in correctly.  In the form there's a combo box; how can I build the "if" statement for checking whether the user picked an item  from it ?</p>
  
  <p>P.S. Sorry for my bad English, it's not my mother tongue. :)</p>