Help with a macro to open to a specific worksheet

[EAHRENS]

s am using the following script to make excel open to a specific worksheet:
Sub WorkBook_Open()
Worksheets("Intro").Activate
End Sub

When A user used the intro sheet, I have a macro that then changes the name
of the file to a user inputted name and then goes to a "table of contents"
worksheet.

I need to write another macro that will then make the file that is now saved
under a different name to open to the "table of contents" worksheet and not
the "intro" worksheet when it is opened a second or successive times.

Does anyone know how to do this. Assume I don't know anything when wording
any answers.