What you need to do in this case is use html form data then process it with a php file
I have been working on this same very issue myself but looking to tackle what I need done in a different manner possibly there are some things I need to figure out myself as well but I am looking to have one box with password protection... I want to do this in LUA.
Anyhow good luck with this project please share anything when you figure out so other people know how to do this as well.
Where I buy my ESP8266 boards from... (Banggood)