Web Interface for my Swift App : I learned how to code in swift a little while back and created my first app. Now I'm trying to market it to customers, I realized that a web-interface might be what I need to scale this up to start attracting clients. 

I use firebase as my backend now and would like to see what I can do to have a web interface that:

Allows customers to log in to see their unique data.
Update info on my firebase backend
is Scaleable.

I'm not sure where to start nor how long this process will take. Any one has any ideas on where to get started?