The best thing to do is throw this project away and start again. The code that is auto-generated by Visual Studio is there for a reason. You can still follow the video, just leave the namespace as it is. If you notice the definition of your
webform2
is declared as
public partial class webform2 : System.Web.UI.Page
The key point being the word
partial which indicates that some part of the class definition exists in another file, which will still have the namespace declaration. Unless you really understand how all the pieces fit together it is best not to try changing it.