CF cannot give you messages, only change formatting.

To have the message shown you would need a formula in an adjacent cell.

Assume A1 is to be red...........in B1 enter

=IF(A1>365,"A1 has exceeded 365 days")

Alternative would be to use VBA event code to pop up a message box and color at
the same time.

Private Sub Worksheet_Calculate()
On Error GoTo stoppit
  Application.EnableEvents = False
  With Me.Range("A1")
  If .Value > 365 Then
.Interior.ColorIndex = 3
MsgBox "Please be advised that A1 has exceeded 365 days"
End If
End With
stoppit:
Application.EnableEvents = True
End Sub

This is sheet event code.  Right-click on the sheet tab and "View Code".
Copy/paste the above into that sheet module.

Edit the range "A1" to suit.

Alt + q to return to the Excel window

Gord Dibben  MS Excel MVP