Consume sharepoint website with webapi

Question

I developed Web app into with SharePoint designer using SharePoint online, so I have views, jquery calls to lists, etc. The problem is I can´t access SharePoint API like this Reference say.

So my manager says that we need to do is to consume SharePoint app into VS web API to give credentials, I´m really new in Visual Studio, what will be my first steps?

I open Visual studio --> New Project --> Web --> ASP.NET Web Application right?

So now what I need to do to do something like these example?

I thing I need to right click solution -->new --> class ?

Help is very appreciated, sorry for basic questions

Answer 1

No need of visual studio if you are using JSOM and Rest Api. if it is sharepoint hosted app then you can use

SP.AppContextSite

to provide host Url and for example you can follow this link