Step 01. Go to the Google developers console https://console.cloud.google.com/getting-started

Step 02. Click "Select a project"

Step 03. Select "New Project"

Step 04. Under "Project Name" type your project name and click "Create"

Step 05. Select "APIS and Services"

Step 06. Click "Select a project"

Step 07. Select the project you have just created

Step 08. Select "Enable APIS and Services"

Step 09. Search for "calendar" and select "Google Calendar API"

Step 10. Click the "Enable" button

Step 11. Select "Credentials"

Step 12. Select "Configure Consent Screen"

Step 13. Select "External" and click "Create"

Step 14. On the OAuth consent screen enter the following information

• App name: type your project name
• User support email: select the available email address
• Developer contact information: enter the email address of this gmail account
• Select "Save and continue"

Step 15. On the Scopes screen select "Save and continue" again

Step 16. On the Test users screen select "Add Users"

Step 17. On the Add Users screen enter the email address of this gmail account

Step 18. On the Test Users screen select "Save and Continue"

Step 19. On the OAuth consent screen select "Back to Dashboard"

Step 20. Click "Credentials", then "Create Credentials" and "OAuth client ID"

Step 21. Under "Application Type" select "Desktop App", type your project name and then "Create"

Step 22. On this screen you can copy your Client ID and Client Secret