Looping a proprietary Add-in to process multiple files

I have a proprietary Add-in that processes a data file, but the Add-in can only process one file at a time. I have many files I need to process and it's too time consuming to do each one manually. Is it possible to write a macro to loop the Add-in so that it can process every file in a selected folder? I've never programmed in VB, but I have some experience in C++, MATLAB, and Python.

This is the rough algorithm of what I'm looking to implement. I have no idea about the syntax I am supposed to use or where to even start the code. Any help is much appreciated

1. Select folder containing files
2. Loop begin
3. Select file to process in Add-in
4. Run Add-in
5. Save and close file
6. Increment to the next data file in folder
7. Go back to step 3 until all data files in folder have been processed
8. Loop ends

Thanks. I'm not sure what you mean by the interface though. I can get into the Add-in's modules through the VBA Editor, but I really don't know what to do or what to look for once I'm in there.

Can I PM you the Add-in if you're interested?

There are 16 modules, 4 forms, and 2 excel objects in it. I apologize for being a total neophyte, but where are subs or function declarations usually found? Is there generally a "main" program or module where you would call up the functions being used? If so, is there a way to tell which file it is? There are no modules with the name "main" or anything that would jump out as the "main" program.