First, you’ll need to create a Google API project and enable its OAuth consent flow. Go to the Google Cloud Console, create a new project, then under “APIs & Services” click “OAuth consent screen.” Fill in the basic app information (name, logo, support email) and add your domain under “Authorized domains.” Once that’s saved, head to “Credentials” and choose “Create credentials → OAuth client ID.” Select “Web application,” give it a name like “My Site Sign-In,” and under “Authorized JavaScript origins” add your site’s URL (for example https://example.com). In “Authorized redirect URIs” put whatever endpoint on your server will handle Google’s callback, e.g. https://example.com/auth/google/callback. Save, and note the Client ID and Client Secret.