for those who struggle to use composer
On web server composer is already installed. open cpanel -> terminal for command prompt
type command
>composer -v
will show you the details of composer installed
https://packagist.org/ helps you the search the packages to be installed
and on top the command to install using composer (to be used after opening terminal from cpanel
example
https://packagist.org/packages/phpmailer/phpmailer
on top of the page command line to be used is shown
i had spent lot of time in finding this and wish to save your time incase you are not aware