Thank you for posting this question!
In order to copy the iframe code:
1. Open the desired widget and click 'Embed':
2. And then, click on the 'iFrame code'. A pop-up message will appear that contains the iframe codes and you can copy them:
Once you copy the code just paste it on the page where you would like the widget to appear on your website.
Please note that some features such as Lightbox mode will be limited with the iFrame code.