Xamarin.Forms GetUser using REST call with username and password (MVC 5 Individual Accounts API)

I am trying to consume a REST service in a Xamarin.Forms PCL app. The REST service is a claims-based, Individual Accounts MVC 5 API. More information on that here. http://www.asp.net/web-api/overview/security/individual-accounts-in-web-api

I've read all the discussions regarding this topic and nothing seems to fit my very specific need.

I've managed to build the app by hard coding some data and bypassing the authentication piece for now.

I'm struggling with the following: I'm also new to development and Xamarin.

1) How to use my Binding UserName and Binding UserPassword from my login Xaml page. I believe it has something to do with UserName.Text and UserPassword.Text.
2) How to Request an Access Token using /Token endpoint and store it.
3) How to use the Access Token when making subsequent API calls.

I also understand that I might have to use something like this to actually store and use the Access Token.
https://github.com/sean-sparkman/CookiesWebView

Any help/guidance is much appreciated.

Thanks!