I've made ads throughout my career for various businesses including retail stores, manufacturers, and service providers. My ads have appeared in newspapers and magazines. Some ads were one-shots while others were part of a larger campaign.
Most of my ads began as scribbling in a notebook. I would jot down ideas that would eventually form headlines, copy, and layouts. I'd flesh out those ideas on the computer using a combination of software packages such as Photoshop, Illustrator and QuarkXPress.
Once finalized the ad designs were rendered as press-quality PDFs and printed in numerous publications the world over.