When you have added the tracking code on the specific site, you can create a campaign and type in the domain of the website you would like the campaign to display on.
Remember that on this first step, you only have to write the domain (e.g. https://www.sleeknote.com) and not the specific URL on which you would like to showcase your campaign (e.g. https://www.sleeknote.com/example).
This is important. Later in the setup you are able to choose which page(s) the campaign is shown on. For example: sleeknote.com/features