We have 2 "modes" for campaign setup. By default you will have "Simple mode" enabled. This means that you only need to enter a campaign name (that will only be visible for you) and upload or create an ad and you are good to go. This ad will be shown once to every visitor that intends to leave your site.
On top right corner you can switch to "Advanced" mode with 3 steps that allow many more settings to fine tune your campaigns.
(You can also switch "Advanced" mode to be your default one in "Website settings")