Are you trying to get the index in an array?
Example:
Sub test()
Dim arr() As Long, i As Long, blnFound As Boolean, lngFind As Long
ReDim arr(1 To 100)
For i = 1 To 100
arr(i) = i * 5
Next
'' find
lngFind = 50
blnFound = False
For i = LBound(arr) To UBound(arr)
If arr(i) = lngFind Then
blnFound = True
Exit For
End If
Next
If blnFound Then
MsgBox i
End If
End Sub