What Would Be A Good Way To Build A Web Application?

For my IT Project Management class, I have to build a web interface for a fictional bank.It's supposed to be a server-side, database driven web application that allows customers to login and access their info and whatnot. I was dabbling around with XAMPP to setup a server, I'm much better with PHP than Java. I don't do these kind of projects often so, I'm not exactly sure how to approach building this application. What would be a good approach to build a web interface in PHP and Mysql?