You reveal job promotions by showing progression in positions under your work experience with a given company. The way to show promotions and accomplishments depends on how closely related your new desired position is to your previous one. In rare circumstances, such as when your role before a promotion was menial and more than 10 or 15 years ago, you may opt to leave it off your resume altogether.
The simplest format is when you get a very direct promotion, such as from marketing coordinator to marketing manager. In this case, you may carry out some of the same tasks, but you also assume a leadership role in a marketing department or team. On your resume, use a bold heading to indicate the company. Under the company, list the most recent position first, with dates, and list previous positions below it on separate lines, with dates. Then, list your most significant accomplishments within the organization as bullet points. Ideally, your best accomplishments are at the highest level, unless the promotion was recent.
Sometimes, people get promoted to higher-level positions, but in different departments or roles. In this case, you should add bullet points under each job title to show distinct accomplishments in each role. Again, start with the most recent position first under the employer heading. If you got promoted from advertising account assistant to media buyer, you would want to identify accomplishments in each role. Your work as an assistant would involve more direct client interaction. Your work as a media buyer involves leading the media planning and buying processes.