There are a few ways to log into Joomla Admin. The simplest way is to open the Joomla Admin site in your web browser and log in using the username and password that you created when you installed Joomla. If you are using a shared web server, you may be able to log in using the username and password of the person who set up the server. You can also log in to Joomla Admin by using the Joomla administrator account.
To create a Joomla administrator account, go to the Administer > Users menu and click on the Add button. Enter your name and email address in the appropriate fields and click on the Create button. When you create a Joomla administrator account, Joomla will create a password for you. You can then log in to Joomla Admin using the administrator account password.