click on it to open its page, where you can read more about it, check out reviews, and view screenshots. If you're happy with what you see, click the "Install" button to begin the download process.
The download process is usually quick, and you'll be notified when the app is ready to use. Depending on the size of the app, this can take anywhere from a few seconds to a few minutes. Once the download is complete, you can find the app on your home screen or in your app drawer, ready to be launched and used.