Period will show your site title at the top of the site by default.
You can replace the site title with your logo by following these steps:
- Visit the Customizer (Appearance → Customize)
- In the Customizer, click on the Logo section
- Click the Select Image button
- Use the media manager to upload a new image or select an existing image, and click the Choose Image button
- Click the Save & Publish button to save your changes
Your logo is now live on your site.