how to use sass in ionic framework?

I am trying to use sass in my project ..I open this link and follow all command .I create a project and set up sass. http://learn.ionicframework.com/formulas/working-with-sass/

I got this directory

   scss
     |
     |—>ionic.app.scss
   www
     |
     |->css
          |
          |——>ionic.app.css

And index.html file I imported ionic.app.css in style tag .So whatever I change in ionic.app.scss file it comes ionic.app.css file and reflect in view .

if I added some element in index.html .Example I added Paragraph tag in ion-contend.

<ion-pane>
    <ion-header-bar class="bar-stable">
        <h1 class="title">Ionic Blank Starter</h1>
    </ion-header-bar>
    <ion-content>
        <pid=“addp”>Testparagraph</p>
    </ion-content>
</ion-pane>

add this

#addp{
background-color:yellow;
}

ionic.app.scss.It added in ionic.app.css and reflect In view.

Now what I try to do .I want to add own file example “application.scss” in sass folder which should create another file “application.css” in css folder .So whatever I code in “application.scss” it come in “application.css” file and I import “application.css” in index.html file .Then It reflect on view .?

where I write this code so I to generate this file and watch the my “application.scss” file .

When I run ionic server and I change anything in “ionic.app.scss” file it reflect on view same time.I need to do same with “application.scss” .If I change “application.scss” .So it will reflect on my view .

I saw this in gulp file.js

var gulp = require('gulp');
var gutil = require('gulp-util');
var bower = require('bower');
var concat = require('gulp-concat');
var sass = require('gulp-sass');
var minifyCss = require('gulp-minify-css');
var rename = require('gulp-rename');
var sh = require('shelljs');

var paths = {
  sass: ['./scss/**/*.scss']
};

gulp.task('default', ['sass']);

gulp.task('sass', function(done) {
  gulp.src('./scss/ionic.app.scss')
    .pipe(sass({
      errLogToConsole: true
    }))
    .pipe(gulp.dest('./www/css/'))
    .pipe(minifyCss({
      keepSpecialComments: 0
    }))
    .pipe(rename({ extname: '.min.css' }))
    .pipe(gulp.dest('./www/css/'))
    .on('end', done);
});

gulp.task('watch', function() {
  gulp.watch(paths.sass, ['sass']);
});

gulp.task('install', ['git-check'], function() {
  return bower.commands.install()
    .on('log', function(data) {
      gutil.log('bower', gutil.colors.cyan(data.id), data.message);
    });
});

gulp.task('git-check', function(done) {
  if (!sh.which('git')) {
    console.log(
      '  ' + gutil.colors.red('Git is not installed.'),
      '\n  Git, the version control system, is required to download Ionic.',
      '\n  Download git here:', gutil.colors.cyan('http://git-scm.com/downloads') + '.',
      '\n  Once git is installed, run \'' + gutil.colors.cyan('gulp install') + '\' again.'
    );
    process.exit(1);
  }
  done();
});