I installed Magento2 without composer. I would like to install a few extensions and another language but all tutorials I have seen use composer.
Is it possible to "add" composer when Magento is already installed ? How do I have to proceed ?
The answer is Yes, you can install it after Magento2 is installed.
First try before to check in console if you have a composer in your server like this:
If command help displays, Composer is already installed else if you have an error message it means that it is not instaled
It's time to install it like this:
curl -sS https://getcomposer.org/installer | php
mv composer.phar /usr/local/bin/composer
Nb: make sure that you're connected as root