How persisting info and steps for http calls

Hi Guys,
I have created my web application, using play framework and mongodb that is working completely connected and well, now i’m developing ionic app for same, but i’m confused here, my confusion is i have created all UI in ionic, but what about data, like for example login and signup, what i have to do about it, in my web application i’m interacting with my data on server obviously, but how to do it in mobile app, i got to know that its HTTP calls but can you please guide me how to go on. Some basic concepts and steps, examples, articles etc.