Before you can start coding your first client application, there are a few things you need to do, if you haven't done them already.
Get a Google Account
You need a Google Account in order to be given access to Compute Engine in the Google APIs Console. If you already have an account, then you're all set.
You may also want a separate Google Account for testing purposes.
Sign up and try out Compute Engine
Follow steps in the Getting Started Guide to sign up for the service, set up a Linux or Windows virtual machine instance, and use the instance to host web content.
It's important to become familiar with Compute Engine basics before you continue. The API documentation assumes you have used Compute Engine and that you're familiar with web programming concepts and web data formats.