title: Running a form for only once in entire Windows form application lifetime
body: <p>In my project i want to show a user-guide when the user first installs my software.So, for <code>only one time</code> i want to show (at beginning) a window where some direction is given so that a user can understand in first time how to use my software.After the user once watches the window(user guide) this window will not appear further time.
  I want to use a form like <code>userguid.cs</code>. this will show in the begging of the mainwindow for one time in the life of the my application. 
  N:B: For example if user restart his computer and again run the app it will not show the userguide window again as it shows before
  How can i do that?? Can anyone give idea how can i do that???</p>