Overview
To allow customers to book appointments online, a booking button or tab must first be added to the website. After successful installation, clicking this button or tab will trigger a window to slide onto the current webpage. This window, called the Booking Widget, is where the appointment-booking happens.
STEP 1: Create the Booking Button(s) or Tab
Multiple buttons can be created and placed in various places on the business website, all which trigger the opening of the Booking Widget. You may also wish to search the WordPress.com Support Center for more detailed instructions.
Create and label the booking button or tab
Check "Link Target" and add '#book-now' as the URL
Uncheck "Open link in a new tab"
STEP 2: Code Injection
Every business has unique HTML code that has already been created. The specific code snippet is located in the business settings (gear icon) > Online Booking > and scrolling down to Booking Widget. Copy the full code snippet to use for the next step. (This script may already have been provided to you).
In Wordpress, add the script into the active theme Header.php file (if you're having trouble finding your Header.php, reference Option 2 in this link). This is usually done by going to Appearance > Editor > Select Theme > header.php > Paste script into the head tag between both <head> lines. If unsuccessful, look for a custom CSS & JS plugin. Be sure to title the addition.
Once the code is injected and saved within the website correctly, clicking the booking buttons should now call the Boulevard booking widget.
For more details, see the specific article from Wordpress.