This guide helps you to build a button that allows your users to connect to your Jcow website using their Google account.

Go to https://console.cloud.google.com/ , If you do not have an account, create one.

From the left-side menu, click the "Credentials".

In the "Credentials" page, click "+CREATE CREDENTIALS" button, then click "OAuth client ID" from the drop-down menu.

Then you can be able to create OAuth ID and secret. You may also be asked to verify your site before you can use it in production.

Once you get your OAuth ID and secret, go to your Jcow Admin CP, in the Configuration page, Google OAuth ID section, input the ID and secret, and click save changes.