Excel helper

I wrote some code in VBA and then customised my toolbar so that in the
<Data dropdown there was an entry that would activate my code.

I then saved my file and all is fine.

The problem: I only want the entry in the Data menu on the toolbar to appear
when I open that specific workbook. At the minute the entry appears in every
excel workbook that I use.

How do I save an excel workbook so that the toolbar is specific tot hat
workbook? Do I need to use an .xlb extension.

Also I wrote my code as Public sub MyCode(). If I instead use Private will
that solve the problem.?

Any help would be appreciated.

Regards


Alex