How to Make a VBA Excel Program Work on Several Documents?

Hi everyone. I'm very new with VBA Excel and i only know the things as far as i need for this report formatting task. My code is almost completed, but what i wonder is, how can i make my program work on several documents?

I mean, i want to choose an excel file via my program, then i want to start the process of report formatting. Then maybe user need to format another document, i want my program to be able to format that document too. how can i achieve that?

Thanks in Advance

Timur

no reply?? Come on guys!