How to Use Interface in vb.net

Public Class User

    Public Property UserID As Integer
    Public Property FirstName As String
    //rest of the properties for user


  Public Sub Save()
   //save the details to the database
  End sub
End Class

and from my UI (its in C#) i do this.

User objUser=new User(); objUser.FirstName="Happy"; objUser.Save();


simple example of how your code could use an interface (using VB.NET):

Public Interface iPerson
    Property FirstName As String
    Property LastName As String
    'Rest of properties for a person

    Sub Save()
End Interface

Public Class User
    Implements iPerson

    Public Property UserId As Integer

    Public Property FirstName As String Implements iPerson.FirstName
    Public Property LastName As String Implements iPerson.LastName

    Public Sub Save() Implements iPerson.Save
        'Add code to save user
    End Sub
End Class

And from your UI you could then do:

Dim objUser as iPerson = New User objUser.FirstName = "Bob" objUser.LastName = "Mckenzie" ctype(objUser, User).UserId = 12345