For each item, the algorithm randomly selects an item at that position or later in the array and swaps the two. This produces a randomized list. See my book for a proof.

' Randomize the list.
Public Sub RandomizeList(items() As Integer)
Dim min_item As Integer
Dim max_item As Integer
Dim i As Integer
Dim j As Integer
Dim tmp_value As Integer

    min_item = LBound(items)
    max_item = UBound(items)
    
    For i = min_item To max_item - 1
        ' Randomly assign item number i.
        j = Int((max_item - i + 1) * Rnd + i)
        tmp_value = items(i)
        items(i) = items(j)
        items(j) = tmp_value
    Next i
End Sub