Where to Start When Making a Web Application on Your Own [closed]

Question

I've been assigned an in-house web application that is basically an Employee and Project Management System.

I'm getting confused as to where I should really start with this assignment (I mean I'm my own development manager and I really don't have experience with making a project alone) and I'm hoping that you guys could share your experiences when you were given an assignment/project to build by yourself.

Thanks