There are a lot of things on the screen and not all of them belong to your application, so "printing on the computer screen" is rather ambiguous. Firstly you need to specify what type of applciation it is.
If it's a Console application then Console.WriteLine will display the specified string in the command prompt window. You would have to have some code after that in order to keep the window open long enough to see it.
If it's a Windows Forms application then Console.WriteLine will display the specified string in the IDE's Output window, but it will not show up in your application's own form. For that you'd need to use a Label or TextBox control and assign the desired string to its Text property.
So... what type of application are you using? What type of project did you select to create in the first place?
