Instructions for logging into Joomla and troubleshooting Joomla login errors and issues. (in process of writing, contact if you need help)
To login to Joomla, use the Users module which comes default as published.
If you can't see it on your site, login as administrator and go to Extensions > Modules. Click 'Search Tools' then select login. If you see a red circle with an X that means your Joomla login module is not published. Click that red circle with an X and wait for it to turn into a green check mark (which means your Joomla login module is now published). Make sure your login module position is selected for an appropriate location on your currently active Joomla template. If you don't know which template is selected, go to Extensions > Templates and check. You should now see your Joomla login module on your site.
Joomla login url
If you want to link to or otherwise directly access the Joomla login page, simply go to yourdomain.com/pathtojoomla/index.php?option=com_users
Joomla admin login
Login to your Joomla administrator area by going to yourdomain.com/pathtojoomla/administrator/index.php