Does anyone know how to add newly created Screen?

These are the general steps.  You should try them on a separate instance of Acumatica that you can play around with so that you’re familiar with the steps.

Assuming that you created the new screen in a different Acumatica instance, you’ll highlight the project in the Customization Projects screen and press the Export button.  That will generate a .zip file containing the details, files, and screens that make up your project.

In the Acumatica instance that you want to install the project to, go to the Customization Projects screen and press the Import button and select the .zip file.  Fill the Publish checkbox and press Save. 

Wait for the users to be out of Acumatica.

Then press the Publish action.