1. Create a Google Developer Project.

To create a Google Developer Project:

1. Go to the Google Developer Console.
2. Log in to your Google account.
3. At the top of the page, click Select a project.
4. Click New Project.
5. Enter a project name.
   
6. Click Create.
7. Select Credentials in the left sidebar.
8. Click Create Credentials.
   
9. Select OAuth client ID.
10. Click Configure Consent Screen.
11. Select External for User Type.
    
12. Click Create.
13. Add the details for your app’s information.
    
14. Add an app domain.
    
15. For each domain that you want to authorize, click Add Domain under Authorized domains and configure the desired domains.
    
16. Under Developer contact information, enter your email address.
17. Click Save and Continue.

2. Create your credentials.

To create the credentials for your Google app:

1. In the left sidebar, click Credentials.
2. Click Create Credentials.
3. Click OAuth client ID.
4. Select Web application for Application type.
5. Enter a name for your OAuth 2.0 client.
6. Enter your full root domain in Authorized JavaScript origins.
7. Enter your full root domain in Authorized redirect URI.
8. Click Create.

3. Save your credentials.

Save the Your Client ID and Your Client Secret values that display in Google after you save your credentials: