Try these simple steps to create random numbers:
create function
private int randomnumber(int min, int max)
{Random rnum = new Random();
return rnum.Next(min, max);}
Use the above function in a location where you want to use random numbers. Suppose you want to use it in a text box.
textBox1.Text = randomnumber(0, 999).ToString();
0 is min and 999 is max. You can change the values to whatever you want.