Ad Server

I want to cross post from one of my wordpress sites to many of my other sites. The documentation seems limited. I am not sure what to do. Add to the “not sure” what to do and the concept of Ad Server comes into the picture. I have YouTubed ad server but it still does not connect the steps for me to know how to cross post. Please add more to the documents pages and reply. Thank you to anyone that can help me in advance. Regards, S Valencia