setting up drush AFTER drupal multisite installed new to drupal and even newer to drush. godaddy shared hosting, I manually setup drupal 8.x multisite where one site is the host account and the rest are subdomains to it. (I didn't use the cpanel install wizard)

I just ssh'd in and setup drush but now I don't understand how to configure it to see all my sites. all the info I've seen relates to setting up drupal using drush, not configuring drush with an existing installation, especially multisite.

do I need to create aliases? any help is appreciated. thanks!
Drush does not need configuration, as long as you run commands from the relevant site folder such as www-root/drupal-core/sites/mysite it will work.

Do check that your version of drush is compatible with Drupal 8 though.