1. In Campaign Management section, click on the Create New Campaign button on the right. 
2. Select your application for campaign, write the name and ID of the campaign and also your description for you. 
3. Click again on your new campaign in Campaign Management section and click on Callback Events pencil on the bottom.
4. Click on the Create New Callback Event button on the right.
5. Turn on your new Callback Event active and also if it is Multiple. In our case is not. Select your Event for this callback (you can find more info how to get Events into the list here). Paste your Callback URL from the Ad Network and improve the link with all necessary Macros. 
6. You can call more Callback Events in the same campaign. Some Ad Networks need for example callbacks for Install Events.