You can create a Hosted Web App in Visual Studio 2015 by following the below steps. Note that you require the existing website to host.

How to Create a Hosted Web App in Visual Studio 2015 ?

1. Launch Visual Studio 2015.
2. Create a new Windows 10 JavaScript app using the Blank template.
3. Open the package.appxmanifest file and set the following
– StartPage of the app
– Application Content URI rules.