csharp for looping

[merhaba]

I am tring to assign random numbers to each 4 label .on my form.but I got stuck.. would you pls fix it ?

private void timer1_Tick(object sender, EventArgs e)
        {
            Random RandomClass = new Random();
            
             for (int a = 1; a <= 4; a++)
             {
               int rn(a) = RandomClass.Next(1, 20);  
                 lb(a).Left = lb(a).Left + rn;
             }
        } 

Thanks