How to load quasar framework Globally

I am new to Quasar framework. Could someone explains how load quasar-components in Globally use. (every where in my application)

My main.js is like:

import Vue from 'vue'
import Quasar from 'quasar'
import router from './router'

require(`quasar/dist/quasar.${__THEME}.css`)

Vue.config.productionTip = false
Vue.use(Quasar) // Install Quasar Framework

if (__THEME === 'mat') {
  require('quasar-extras/roboto-font')
}
import 'quasar-extras/material-icons'
// import 'quasar-extras/ionicons'
// import 'quasar-extras/fontawesome'
// import 'quasar-extras/animate'

Quasar.start(() => {
/* eslint-disable no-new */
 new Vue({
  el: '#q-app',
  router,
  render: h => h(require('./App').default)
 })
})

Unknown custom element: <q-btn> - did you register the component correctly? 
For recursive components, make sure to provide the "name" option.

 found in

---> <App> at src\App.vue
   <Root>