The application will be started with a command line argument. You need to process that argument.
There is an item in
VB Command$, that hols the entire command line.
If you have a routine (on a menu pick, or whatever), trigger that routine with the filename you find in the command line.
By the way, please read Dougâs link (above), "Read this if you want to know how to get a correct reply for your question," regarding choosing a subject line; I believe it will make a lot of sense to you.