The recommended way to start a new Vaadin project is to use Vaadin Start. It allows you to configure and download a customized starting point for your application.
The applications created using Vaadin Start are based on Spring Boot. Vaadin Flow starters for other stacks, such as JavaEE or plain servlet, are available in GitHub.
More Vaadin starter projects are available on GitHub.
Once you have downloaded a starter project and have it extracted in a local folder, you can import it to your favorite IDE (integrated development environment) and start developing it further.
If you create a project outside an IDE, you need to import it in the IDE. During development, you can run the project with a Maven target, depending on the technology stack you are using.
After you have the project in your IDE, you can go ahead and run or debug it.