HTML stands for Hyper Text Markup Language, and it is the building block of every website. Certain websites supply their clients with HTML code which they can use on their websites. Subscription boxes for instance, would make use of a code from their mail service partners.
On your builder, click on the Advanced button.
Once your Item box appears, click on the Custom HTML button.
An empty box will appear, double click on this box or right click and select properties.
Once your properties box appears, enter your HTML code in the code box.