ShellExecute is a feature in windows dll. You need to add an ad for it, like this in a VBA module:
Public Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" ( _
ByVal hWnd As Long, _
ByVal lpOperation As String, _
ByVal lpFile As String, _
ByVal lpParameters As String, _
ByVal lpDirectory As String, _
ByVal nShowCmd As Long) As Long
Shell ShellExecute , ShellExecute URL-, . IE. IE. iexplore.exe . ShellExecute url windows.