Affiliates can use the Ads you prepare for them. An Ad is basically a picture you upload which is linked to either the shop in general (to be precise - the catalog view of a Theme) or a certain project of a Theme.
Ads can be uploaded under ‘Marketing -> Affiliates -> Manage Ads’
Typical ad sizes are listed below. Although the system does not restrict you from using different sizes, this is not recommended because typical Affiliates will not have their web sites designed to work with different sizes.
Confirmed Affiliates can view your Ads and retrieve an HTML code snippet for the integration into their web site(s).