Option Explicit
Sub cerca_trova2()

'dichiaro le variabili
    Dim wk1 As Workbook, wk2 As Workbook
    Dim sh1 As Worksheet, sh2 As Worksheet
    Dim Area1 As Range, Area2 As Range, cella As Range
    Dim nonesiste, valore

'metto i riferimenti ai files
    Set wk1 = Workbooks("FileExchangeCatalogTemplate.xls") 'non hai messo .xls
    Set wk2 = Workbooks("Ricerca.xls")
    'metto i riferimenti ai fogli
    Set sh1 = wk1.Worksheets("Foglio1")
    Set sh2 = wk2.Worksheets("Ricerca")
    'metto i riferimenti alle Aree
    Set Area1 = sh1.[D2:D49]
    Set Area2 = sh2.[C3:C50]
    
    For Each cella In Area2

        valore = cella
        Set nonesiste = Area1.Find(valore, LookIn:=xlValues, LookAt:=xlWhole) ' Set wk1 = [D:D].Find... casomai era sh1
        If nonesiste Is Nothing Then
            cella.Interior.ColorIndex = 3   'rosso nonesiste
        Else
            cella.Interior.ColorIndex = 36   'giallo chiaro esiste
        
            End If
    Next
  
    'Set a Nothing delle variabili oggetto
    Set sh2 = Nothing
    Set sh1 = Nothing
    Set wk1 = Nothing
    Set wk2 = Nothing
End Sub