VB.NET supports
String.ToCharArray. You can use it to change a string into an array of characters so you can easily iterate through them:
Dim intCounter As Integer
Dim chrArray() As Char
chrArray = strInput.ToCharArray
'Iterate through the string.
For intCounter = 0 To chrArray.Length - 1
MsgBo>:chrArray(intCounter))
Next
End Sub