How to install git and set environment to enable phpmailer to install on windows 10

hi friends,

i have been trying to send email via localhost using phpmailer and base on research, i was ask to first install composer and set the environment variable. i downloaded and composer from https://laravel.com/docs/5.4  and set the environment variable. the problem is when i try to run (composer require phpmailer/phpmailer) again,

i am still getting this error

[RuntimeException]
  Failed to clone https://github.com/PHPMailer/PHPMailer.git via https, ssh protocols, aborting.

  - https://github.com/PHPMailer/PHPMailer.git
    Cloning into 'C:\xampp\htdocs\vendor\phpmailer\phpmailer'...
    fatal: unable to access 'https://github.com/PHPMailer/PHPMailer.git/': Could not resolve host: github.com

  - git@github.com:PHPMailer/PHPMailer.git
    Cloning into 'C:\xampp\htdocs\vendor\phpmailer\phpmailer'...
    ssh: Could not resolve hostname github.com: Name or service not known
    fatal: Could not read from remote repository.

    Please make sure you have the correct access rights
    and the repository exists.


require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]...

i have install git but it still not working. please help! i am new to web development