Banners
Banners could be used for a variety of things, including giving a more prominent placement to sponsors, but basically provide an easy way to create a large button in a prime viewing area with a link to more information about something.
Navigate to Content - Advanced Features - Banners. Click View List/Add New to create a new banner.
There are 3 types of banners: Image, Text and Countdown. Select which one you would like to use.
Fill out the required information and hit Insert.
You will see a preview of your banner. You can make edits to it by double clicking directly on it or delete it by hovering over it and selecting the trash can on the far right.
You now need to tell the website where you want the banner to show. Navigate to Banners - Current Banners and click on your banner.
Double click where you want the banner to show and hit update. Could be on the Main Site or any of the other levels of the website (Team Site, League site etc)