Building an app . . . how do I start?

My latest project is to build a web app for podcasts.

I’m a podcast fanatic and just think it would be cool to have something I built for something I love.

So where am I supposed to start?

Well, I love a good outline . . . so I drafted this up. I will be following this path to my app. I found it here: https://css-tricks.com/app-from-scratch-1-design/

I. Planning the App: Idea and Design

II. Planning the App: Database and Development Approach

III. Designing the App: Workflow Map and Design

VI. Designing the App: HTML and CSS

V. Developing the App: User Interaction

VI. Developing the App: AJAX Interactivity

VII. Developing the App: List Interaction

VIII. Security

Any advice or help along the way would be fantastic!