There are several platforms and tools for creating online advertising. One popular way is to use the Google Ads advertising platform, where you can create and customize search, display network, or video ad campaigns. To create ads on social media such as Facebook or Instagram, you can use business accounts on these platforms and customize your ads through their tools. It's important to define your ad campaign goals, select your target audience, create an engaging ad, and set your ad delivery settings (placements) correctly to achieve the best results.