Most templates allow for a container that displays on top of the homepage carousel item. That container is most commonly used for a sign-up. Here is an example of that item in use in a standard template:
You can customize this item in various ways by editing the html code.
Alternatively, there are several other sign-up items available in the standard inventory. You can also easily click and publish these items. To explore this option, follow these steps:
Starting from the admin panel / website area, edit and manage
proceed to 'Homepage', then click 'Browse Inventory'
Scroll down until you see items named Signup_inslider_*
You can review the description, view a screenshot for each.
To publish one, click the plus icon
This should call the inventory item, populate your new item
Alter the container to 2s and click save
If you have another item in the 2s container, you will need to remove it.