We are working on fully automating this. If you install the Command Task Runner in Visual Studio 2015, you can deploy the functions to a previously created function app using the deploy.ps1 script found in the solution's Deployments folder.
In the meantime, here is one way to set it up by hand.
Manual Creation and Configuration in Azure
Click the image below to watch the video.
Note the video is already out of date with respect to function names and config file format, but if you use the structure of the sample config file you should be fine.
Creating and Configuring a SharePoint Add-in
Receiving Events in Custom Client Back-ends