algorithm/decrypting - i think--need help!!

So you need help solving those cryptograms. Well, this should
get you started. It will replace the most commonly occuring letter
with an "e". Just paste this code to a form with 2 text boxes
(Text1,Text2) and a command button (Command1).

Code:

---

Option Explicit
Dim sEncoded As String

Private Sub Form_Load()
  Text1.Word
  'make sEncoded any string you want to decode
  sEncoded = "fzdQlkzqfLLWzEOQzFLzFlQzqgorZtyqZZitQfziqzQitzytZITOZIYTiZtyZSoto"
End Sub

Private Sub Command1_Click()
  Dim i, iNewStart, iCount, iHigh As Integer
  Dim sCompare, sMostCommon, sDecoded, sReplace As String
  Dim aLetterCount(26) as Integer 'alphebet
  Text1 = sEncoded
 
  'find most common letter in encoded text
  For i = 65 To 91 'ascii #s for letters
    sCompare = Chr(i) '(65)=A Chr(97)="a"
    iCount = 0
    iNewStart = InStr(1, sEncoded, sCompare, vbTextCompare)
    Do While iNewStart <> 0
      iCount = iCount + 1
      iNewStart = InStr(iNewStart + 1, sEncoded, sCompare, vbTextCompare)
    Loop
    'make record of # of time a letter occurs
    'aLetterCount(0) is the # of times "A" or "a" occurs
    'aLetterCount(25) is the # of times "Z" or "z" occurs
    aLetterCount(i - 65) = iCount
  Next i 'check next letter
 
  'replace the most common letter with "e"
  For i = 0 To 25 'letters in alphebet
    If aLetterCount(i) > iHigh Then iHigh = aLetterCount(i)
  Next i
  For i = 0 To 25
    If aLetterCount(i) = iHigh Then
      sMostCommon = Chr(65 + i)
      sReplace = "E"
      'Replace(expression, find, replacewith[, start[, count[, compare]]])
      sDecoded = Replace(sEncoded, sMostCommon, sReplace, 1, -1, vbTextCompare)
      Text2 = sDecoded
      MsgBox "The most common letter is: " & sMostCommon & vbCr & "It was replaced with: " & sReplace
      Exit For
    End If
  Next i
End Sub

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Note that the # of occurances of each letter are stored in an array
so you can check the 2nd most common occurance, the 3rd, and so on.
Have Fun.