Userform Log-in; Excel Hide and Unhide?

Hi Guys,

I am planning a little tool using userform in VB excel. What I really want to do is:
When I double-click the excel icon (means the Macro-enable Excel File; not the actual excel application) in my desktop I want UserForm named “Log-in” to initialize and excel workbook should be Visible = False.

Next when the user is Loged-in by appropriate ID and password the userform should disappear and excel workshhet named “Interface” should show-up - WBVisible = True

How can I achieve this? I know how to do the log-in userform but looking some help in hiding and reappearing excel workbook.

Basically, at the beginning I do not want excel to show up, only the userform “log-in” should be visible and once log-in excel should be visible and user-form should disappear. Thanks a lot.