In the admin Marketing > Banners
Name The required name of the banner
Store If you have a multi-store version, which store front can accept this banner image
Pos Sequence number of displaying multiple banners on the site from 0 onwards
Type Either an image or text banner
Image Upload the banner from local, server or URL
Open in new window Have the banner link to a page in new window or not
URL The URL if link from the banner is required
Creation date When banner created
Status Active, Hidden or Disabled
And select Create on the menu to save to the banner list.
You will then need to add the banner to the home page block.
In the admin Design > Layouts > Homepage
You will need to find the banner block in the page layout, this should be titled accordingly. Select the cog icon on the block.
Select Content and add your new banner, then save.