To create and monetize an app, first develop a clear idea for the app that provides a solution to a problem or meets a need in the market. Then, design and develop the app, keeping the user experience and interface in mind. Next, choose a monetization strategy such as in-app purchases, subscriptions, or in-app advertising. Finally, market the app through app stores, social media, and other channels to reach a wider audience and generate revenue. Continuously update and improve the app to maintain user engagement and grow revenue.