Write an A4 document in WinForm Application using c#

Write an A4 document in WinForm Application using c#

Just wondering how to write an original of an A4 document in WinForm
Application. For example I can click a button and then it loads into
WinForm Application an original document. It should load the original from
a MS Word document. So that I don't have to write the document manually.
I'm programming in c#.
Thanks for every single answer
PS: I just wonder if it's possible and how I have to start or what I have
to look for. I don't have some code :)