Go to WP Menu => Appearance => Customize
After clicking on customize you will in theme Customizer.
Here you have to click on Front Page Section than Appointment Section
Go to Customize -> Frontpage Section -> Appointment Section -> Header -> ShortCode
As you can see in given below image paste your shortcode in textarea.
Go to WP Menu => Appearance => Customize
After clicking on customize you will in theme Customizer.
Here you have to click on Front Page Section than Appointment Section
Go to Customize -> Frontpage Section -> Appointment Section -> Content
As you can see in given below image you can change image,contact info,button text and button link.
After making change click to publish.