shamsudeen once connected to SSH, you use the cd command to move to the correct folder.
You can use the ls command to see the content of the current directory and confirm you are where the config.php file and the flarum extension-less file are found.
Your host probably gives you access to a lot of standard bash/shell commands like these ones. You should be able to find tutorials for these online, probably titled Linux shell tutorial for beginner, or similar.
If Composer produced no output at all, there's probably a system limitation. You should ask your hosting support whether Composer is supported over SSH. You can also download your own composer.phar executable to use over SSH if the host doesn't provide you an up to date version.
