You can show the banner to the portal users by choosing the specific template on the customer portal main page (home page). When the portal users access the customer portal, they can see the customer portal banner as configured using the “Banner” widget from the portal admin side.
Banner with Content only
You can choose the template that you want to show as the portal’s home page to the portal users. If you have chosen the content-specific template only, you just need to set the Banner’s Header Text and Sub Header Text only. 
Banner with Image
You can choose the template with the image as well.
In the screenshot , the content is on the left and the image is on the right side as per the selected template. You can also choose the template in that the image will be on the left side and the content will be on the right side.
Button for CTA
If you have enabled the button from the portal admin side in the “Banner” widget, the portal users will get the button and navigate to the button events as configured. (Specific page of the portal or external URL) 
Banner with the specific background
You can set the banner’s background by setting the background color (solid/gradient), Image (uploading an image), or Video (uploading a video/external video URL) as per your requirement of the portal. 
Banner with Gradient color background:
The banner is set as a gradient color background choosing the Primary, Secondary Color and setting the gradient degree. 
In this way, you can also show the banner with the background video.