A program that ask you wich web browser you want (Help)

I want to make a simple program that ask you wich browser you want to use. When you'll click on a link (email or pdf for exemple), a program will appear instead of the browser and will ask you wich browser you want to use.

First : in wich code it's the best to write this? Secondly : How to open the program and not the browser?

I need a bit of help to write this, because i don't know how begin