Excel 2007 : How I implement a code?

Hi,
I have found this code on the internet but I don't know how to make it to funtion.
Can anyone tell me what do I have to add in the beggining and in the end to make it work.
Thank you!

Function SplitText(str As String, iPart As Byte, iMaxChars As Integer) As String
    
'  ______________________________________________________________________________
' |                                                                              |
' |  Wim Gielis                                                                  |
' |  wimmekegielis@hotmail.com                                                   |
' |  06/09/2007, revised 06/10/2007                                              |
' |  Custom function to split text in parts. Words are not broken, and you       |
' |         can specify the maximal number of characters in each part            |
' |  Also on http://www.wimgielis.be                                             |
' |______________________________________________________________________________|
    
    
    Dim arrWords As Variant
    Dim iWordCounter As Integer
    Dim j As Integer
    Dim iPartCounter As Integer
    Dim sConcatTemp As String
    
    If iPart < 1 Then
        SplitText = "Part number should at least be 1"
        Exit Function
    End If
    
    SplitText = ""
    
    If str <> "" Then
    
        str = Trim(str)
        str = Replace(Replace(str, Chr(32), " "), Chr(160), " ")
        str = Replace(str, "  ", " ")
        
        arrWords = Split(str)
        ReDim Preserve arrWords(UBound(arrWords) + 1)
        arrWords(UBound(arrWords)) = "a" 'dummy to avoid an error message later on
        
        iPartCounter = 1
        j = 0
        
        Do While iPartCounter <= iPart
            iWordCounter = 0
            sConcatTemp = ""
            
            Do While Len(sConcatTemp) - 1 <= iMaxChars And j + iWordCounter < UBound(arrWords)
                sConcatTemp = sConcatTemp & " " & arrWords(j + iWordCounter)
                iWordCounter = iWordCounter + 1
            Loop
            
            If Len(sConcatTemp) - 1 > iMaxChars Then iWordCounter = iWordCounter - 1
            
            If iPartCounter = iPart Then
                If Len(sConcatTemp) - 1 > iMaxChars Then
                    SplitText = Trim(Left(sConcatTemp, Len(sConcatTemp) - Len(arrWords(j + iWordCounter))))
                Else
                    SplitText = Trim(sConcatTemp)
                End If
            End If
            
            iPartCounter = iPartCounter + 1
            
            If j + iWordCounter = UBound(arrWords) Then Exit Function
            
            j = j + iWordCounter
        Loop
    End If
End Function