There are several ways to create add banners to your page - you can create custom widget which to display&rotate images. For creating custom widgets you can check this video
and Sitefinity documentation
In Sitefinity documentation there is a NewsRotator control tutorial
which is closest to what you seek.
I would advise you to check this
blog post which is about managing ads using Module Builder in Sitefinity
I hope that my answer was informative enough, should you have any other inquires or problems, do not hesitate to contact me.
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