Unable to install laravel 5 on windows via composer

I am trying to get started with laravel on windows and here is the command I tried:

rahul@rahulserver MINGW64 /d/PhpIdeaProjects/LaravelLearning $ composer create-project laravel/laravel learning-laravel-5

Here is the output I get:

Installing laravel/laravel (v5.0.22)
  - Installing laravel/laravel (v5.0.22)
    Loading from cache

Created project in learning-laravel-5
Loading composer repositories with package information
Installing dependencies (including require-dev) from lock file
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for danielstjules/stringy 1.9.0 -> satisfiable by danielstjules/stringy[1.9.0].
    - danielstjules/stringy 1.9.0 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
  Problem 2
    - Installation request for laravel/framework v5.0.16 -> satisfiable by laravel/framework[v5.0.16].
    - laravel/framework v5.0.16 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.

So how shall I move on and have it working?

via Chebli Mohamed