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 145×53 pixel.
This theme support another header type called transparent header. For transparent header you can use another logo image.
For uploading the transparent header logo go to the Theme Option > Header Settings. Here you can upload the transparent header logo.
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 for update those information. Make sure you update the site email address.