The human and mind variables are only visible inside the Main method. To do what you want you need something like this:
class Practice
{
public static string human;
public static int mind;
public static void Main()
{
human = "Walking & talking life";
mind = 100;
}
}
class Continued
{
public static void notMain()
{
MessageBox.Show(Practice.human);
MessageBox.Show(Practice.mind);
}
}