For changing the logo, navigate to the Appearance > Customizer. Go to the Site Identity tab. Here you can upload your Logo.
For best result use resized logo image, Suggested size is a 110×38 pixel.
You can update the information ( site title and tagline ) form customizer and the general settings.
If you see the logo change screenshot you can see the site information input fields as well.
If you want to update those information form the general setting, Navigate to the Settings > General settings.
Here you can see the input fields to update the information. Make sure you update the site email address.