Seeking Senior Project Advice

Hey HN,

I'm a senior CS student and I'm currently working on my senior project. Our group decided to go with my idea and I'm having trouble conceptualizing what we're going to need to develop. I haven't really had much experience building a project of this scope before. I was wondering if any professional developers would mind lending me some of their wisdom on how to prototype/develop a semi-ambitious web-app?

Thanks, Stressed CS student