All promotional materials can be managed in the merchant panel in Banners -> Banners manager.
In Banner Manager you can find few sample banners already created which show you how it is done. You can edit or delete those and you can also create a new ones. Every banner belongs to a particular campaign that it promotes.
You can start creating a new banner by click on 'Add banner' button above the banner list. From the next screen you can choose the type of the banner.
If you can't find some type of the banner here, you have to activate it first in the Features section.
When creating a banner it is absolutely enough to fill in just the required fields so in most cases the banner name, the destination URL and image. You don't need to worry with all the other optional/advanced options. As for the destination URL in 98% of cases you do not want to add any advanced variables to the destination URL, you simply want to insert the full URL address (including HTTP(S) protocol) of the site which will be promoted by the banner, so for example if I wanted to promote our website then I'd just enter https://www.postaffiliatepro.com/ and all the tracking parameters will be added automatically by the system.
Advice: Pay attention to your promo materials, it is something that represents you. They should be interesting enough to attract the visitors to click on them to find out more.
Here is the video tour:
Continue to the next step of setting - 6. Set up emails functionality