App Inventor is a cloud-based tool, which means that you can build apps right in your web browser.
If you want start your first program you must click here and clicking the orange “Create” button on this website.Complete the sign up and login with your email.

My first APP named “HelloWord”

The bottom used to design your APP’s interface and if you click the   bottom you can design you APP’s logic link that.

If you have a computer, an Android device, and a WiFi connection, this is the easiest way to test your apps.To do live testing on your Android device just install the MIT App Inventor Companion app on your Android phone or tablet.  And you can test your apps as you build them:

After you click”AI Companion”  you can see

and then scan the barcode or type in the code to connect for live testing of your app.