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