how to composer require version code example

Example 1: composer require with version

composer require vendor/package:version

composer require refinery29/test-util:0.10.2

Example 2: upgrade composer

To update composer command just find location of composer.phar and update as:
 where composer 	#Retrieves you location of your composer.phar
 cd path_to_composer.phar #Move to directory with composer.phar
 php composer.phar self-update	#Update your composer