Step 1: Select the placeholder option
- Select the last option under the "position" setting in the bar configuration in the App
- Check the "Pin the bar" option
- Scrolling to the very end, and click the "Save" button to save the change

Step 2: Add the bar part I
- Go to Admin > Online Store > Themes
- Click the "Actions" button on the right-hand side, and select "Edit code"
- Find static-header.liquid from the left-hand side file list and open it
- Find <div class="site-header-wrapper
- Add following codes before it and save the changes.
<div id="qab_placeholder"></div>

Step 3: Add CSS
- Find theme.scss.liquid from the left-hand side file list and open it
- Scrolling down to the very end of the file
- Add following codes at the very end of the file and save the changes.
#qab_background{top:0;z-index:1000 !important;}

Enjoy the app
Congratulations. The integration is done.
If you cannot see the bar yet. Please double check Step 1 and make sure you save the settings.