If you want to add magazines to your WEBKiosk or APPKiosk you need to connect a collection to that WEBKiosk or APPKiosk. The collection can contain multiple sections, which each can contain multiple magazines.

Go to "My Publications".

Scroll down to your "Collections" and click on the "Setting" icon at the collection you want to connect with your WEBKiosk or APPKiosk.

Then click on the "Connect" button and choose the Kiosk you want to connect to your collection. Now you can use that collection in the Kiosk.

Here is a tutorial about the WEBKiosk editor