You’ve defined the project goals in broad strokes and are talking to someone that can build your web application. The next step is to plan the first stages of the project so that you can start shipping software.
You have a developer and a clear set of requirements to get your project started. Now you need to begin shipping software.
By “shipping” we mean going through the process of implementing your requirements and deploying it to somewhere you can interact with it…
You want to build a web application that solves a business problem. You’ve got some ideas in your head about how it could work. You want to translate these ideas into working software.