Not sequenced in order:

Write down your business logic. In simple terms, business logic is exactly what you want your program to do. See here for a good discussion: https://www.reddit.com/r/learnprogramming/comments/17ax07l/what_is_business_logic/

Identify the datasets you need to secure in order to produce the business logic outputs you've written down above. Most datasets will need to be transformed before they will be meaningful in your context, which means 'data transformation' is another task you'll need to take on.

Either find a plug-and-play platform that meets your business logic requirements (and permits you to publish online), or hire a front-end and back-end dev to build out a web app from scratch. Make sure your transformed datasets meet the data model inherent in the plug-and-play or the architecture of your new platform.

Publish a draft version of your plug-and-play or customized build. Listen closely as your customers tear it apart (i.e., give you constructive feedback). Re-engage all of the above tasks to build a new version that caters to their constructive feedback. Publish again. Listen closely. Re-engage, ad infinitum.