RestSharp is an open source REST client for .NET. I will use it for consuming Google Data API. You can easily install via the following NuGet command

Install-Package RestSharp

First step is creating an application in API Console and selecting services that you will be using. In this example, we will use the Tasks API. Once you create your project with the appropriate settings, you will need client_id and client_secret which is available on the API Access page. read more »