By the way you only need to create one instance of the Random class and call it's Next method to create another random number.
vb.net Code:
Public Class Form1
Dim rand As New Random
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'Generate random number between 1 and 10
Dim randomNumber1 As Integer = rand.Next(1, 11)
'Generate random number between 50 and 100
Dim randomNumber2 As Integer = rand.Next(50, 101)
'Generate random number between 500 and 1000
Dim randomNumber3 As Integer = rand.Next(500, 1001)
Label1.Text = "Random number1: " & randomNumber1.ToString & " Random number2: " & randomNumber2.ToString & _
" Random number3: " & randomNumber3.ToString
End Sub
End Class