Are you looking to build a faucet script completely from scratch or do you want to customize one that is already made? Building one from the ground up does not seem too easy in my eyes. I would guess it's written in C++ and HTML. Hopefully, someone with more knowledge in website design can help you out here.
I do not think you need C++ for a faucet.
Typically you would use html and php+mysql with api knowledge as a bare minimum