You can manage all your campaigns on the campaigns list page. It is the entry point to everything you can do with campaigns and it has a bunch of nice features to offer.
The first thing you might want to do is create a campaign. Click on the "new campaign" button, give it a meaningful name to find it later in the list and you will see the campaign creation tool.
In the list itself, you have a number of useful information to gauge the success of your campaigns like the impressions rate, the interactions and the CTR.
(a developper)
With a just a click on the published switch, you can activate a campaign and display it immediately to your guests or remove it from the portal template.
By clicking on the pen you can edit your campaign and modify it to better suit your need and increase its popularity.
If you don't need a campaign anymore, just click on the trashcan to delete it.
If you click on a particular campaign, it will open the details pane. It contains all the targeting information for this campaign, its positioning on the template, a thumbnail of the media associated if there is one and a reporting that shows you how your campaign fares over time.