Launch Microsoft's Visual Studio.
Create a new project or open an existing.
In Solution Explorer right click "References" and "Add Reference":
Add reference to SautinSoft.Document.dll.
(The Library located in the subfolders of the folder "Bin" of the Package "Document .Net Trial (N.N.N.N)" For example: Bin\Net 4.0\SautinSoft.Document.dll or Bin\Net 4.5\SautinSoft.Document.dll.
Well done! Now your application is able to do all what you want with DOCX, RTF, PDF and Text documents!
Here you will find the Collection with Code Samples in C# and VB.Net.