Homeassistant UI

I am trying to customice the UI of Homeassistant that I have .I have downloaded the polymer from the link given in the documentation but whenever i open the modified html files nothing happens .What should I do?

Also can someone tell me from where do the backend code open the UI?

Ayushi, or Hautomation769, whatever your name is today, have you ACTUALLY read the developer documentation? Why do you keep posting these types of questions? Why do you open so many threads?