After All the setup, To make Hello World App
ionic start HelloWorld blank  // create new project
cd HelloWorld                 // get into HelloWorld directory
 <body ng-app="starter">
   <ion-pane>
     <ion-header-bar class="bar-stable">
       <h1 class="title">Ionic Hello World App</h1>
     </ion-header-bar>
     <ion-content>
        <div class="center">Hello World..!</div>
     </ion-content>
    </ion-pane>
 </body>
ionic serve                  // run the app in browser
ionic platform add android   // add android platform
ionic platform add ios       // add ios platform
adb devices                  // to check devices is connected
ionic run android            // to run on android devices
ionic run ios                // to run on ios devices
ionic run android -c -s -l    // to check app in live reload with console.