Random rand = new Random();
Mas = rand.Next(1, 7)+6;
label6.Text = Mas.ToString();
Vin = rand.Next(2, 13) + 12;
label7.Text = Vin.ToString();
Ud = rand.Next(1, 7) + 6;
label8.Text = Ud.ToString();
int i = 5;
// или
double localF = _globalF;var c = new MySuperLongClassName();
// или
var lm = new List<Model>();