Hi Aaron,
Welcome to the forum.
As you are experienced with HTML and Asp.net related and would like to build a web application base on a pre-existing one, I would suggest you go through the migration documentation:
Migrating a web app or
Migrating a website.
I think the best practice for you is to style the app interface and querying the data AJAX, however if you are interested with Windows Store App Authentication, you can also ref to the sample:
https://code.msdn.microsoft.com/windowsapps/Web-Authentication-d0485122
--James
We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
Click
HERE to participate the survey.