adding breadcrumbs

I have been getting to grips with the Childishly Simple theme and have tried to activate breadcrumbs using Yoast SEO plugin. I have read the support topic – http://wordpress.org/support/topic/how-to-add-yoasts-breadcrumb?replies=6 – but have failed to crack it just yet.
Where can I find the ‘header container’? Is this part of the themes options page? Any help/pointers would be much appreciated. In case you need it the web site is http://www.cypruscountryholidays.com

Thanks

https://wordpress.org/themes/childishly-simple/