With couple sample screens for better understanding You can find sample screens right here Screens page.
Open the App.js file to start writing some code. You can preview the changes directly on your phone or tablet by clicking the Run button or use the simulator by clicking Tap to Play. When you're done, click Save and share the link!
When you're ready to see everything (or if you want to use your own editor) you can Export your project and use it with expo-cli.
Snack is Open Source. You can find the code on the GitHub repo.