First of all we have set up development environment before doing anything in AngulaJS.
Install Node.js® and npm if they are not already on your machine. After installing nodeJS run the following command or go to https://cli.angular.io/ for more details
npm install -g @angular/cli
ng new my-app
You will see a successfully compiled message and open this link in your browser http://localhost:4200/. So thats it you have setup your environment and your first app in Angular in running.