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
- Go to Admin > Online Store > Themes
 - Click the "Actions" button on the right-hand side, and select "Edit code"
 - Find header.liquid and open it
 - Add following code at the very top of the file and Save the changes.
 
<div id="fsb_placeholder"><script>var fsb_adjusted = false;$( "#fsb_placeholder" ).on( "fsb_fully_loaded", function(event, p1) {if ((p1=='inserted' || p1=='inserted_sticky') && !fsb_adjusted ){fsb_adjusted = true;var fsb_height = $("#fsb_background").height();$("<div />", {html: '<style>' + 'div#header-wrapper.inline-header{top:' + fsb_height + 'px !important;}' + '</style>'}).appendTo("body");}});</script></div>

Enjoy the app
Congratulations. You successfully integrate the app with your theme.
If you cannot see the bar yet. Please double check Step 1 and make sure you save the settings.