Hi Shari,
Thanks for reaching out with your BoldGrid Post and Page Builder questions!
If you add your custom HTML directly to the widget area in your theme it will appear globally. In order to add a custom widget to a homepage you’ll need input the form directly into your page in the Post and Page Builder.
Simply find the area on your page where you’d like to add your HTML and switch to the “Text” editor of Post and Page Builder to add your HTML. After adding your HTML switch back to the “Visual” editor to inspect your changes.
I hope this helps!