1) Access modifiers in C# are different from C++ in that you need to explicitly specify one per class member.
http://msdn.microsoft.com/en-us/library/wxh6fsc7(v=vs.71).aspx
2) The get, set you are mentioning refer to C# Properties:
class User
{
private string userName;
public string UserName
{
get { return this.userName; }
set { this.userName = value; }
}
}
Pls note that you can also use auto-implemented properties http://msdn.microsoft.com/en-us/library/bb384054.aspx
3) Subclassing in C# is done like so
class Manager : Employee
{
//implementation goes here as usual
}