I made a video where i explain how to connect and read tags from and Opc server using OpcNetApi.dll library with C#.
This post follows a serie of old article that you can read on my old blog.
This code comes from Beckhoff OPC how-to section and if you run a google search of some parts of the code you can find more references and tips about implementing different functions of the API.
You can watch the video here:
Get the sample code
Also you can download the sample application from GitHub.