In the overview in the 'Creatives' tab on a campaign, you will see a list of all creatives created for that campaign
From this overview, here are some of the most important features you can utilize:
Add campaign booking - This button will be activated (turn green) once at least one creative has been added to the campaign. The offer booking is by far the preferred booking option. For a detailed guide, go here: Campaign Booking
Add new - To add a new creative to the campaign, click here.
Book - To make a booking only for a specific creative, click this button. For a detailed guide, go here: Creative Booking
Edit - To edit an existing creative, click here.
Copy - To make an identical copy of a creative, click this button. The copied creative will keep all content and settings of the original creative, but will not have any statistical data.