Open the Google API Console Credentials page.
Click Select a project, then NEW PROJECT, and enter a name for the project, and optionally, edit the provided project ID. Click Create.
On the Credentials page, select Create credentials, then OAuth client ID.
You may be prompted to set a product name on the Consent screen; if so, click Configure consent screen, supply the requested information, and click Save to return to the Credentials screen.
On the page that appears, copy the client ID and client secret to your clipboard, as you will need them when you configure your client library.