Nuget package url: https://www.nuget.org/packages/NetCore.Simple
Using visual studio you can add the nuget package netcore.simple and the bower netcore-simple. Alternatively you can install with command line as follows
dotnet add package NetCore.Simple bower install netcore-simple
Once installed, move the contents inside wwwroot/lib/netcore.simple/View templates templates to Views/Shared/. You can modify the file contents as desired. This folder includes a _Layout.cshtml file to rewrite the layout with the required changes. If you choose to update the layout manually, you can do the following.
You need to import the css (\wwwroot\lib\NetCore-Simple\css\style.css) and js (\wwwroot\lib\NetCore-Simple\js\scripts.js) files. You will also have to import the js and css for jQuery, bootstrap and angular. Once all js and css have been added, you can create an angular module, lets say "app" which would look something like this: