When your hosting account was setup, your hosting provider or system administrator should have provided you with the address (URL) to your Plesk login page, as well as your username and password.
Typical Location of Login Page
Most web hosts are set up to use the following links (URLs) for their Plesk login page.
Domain is Pointed & Working
If your domain name is already pointed to your hosting account, you typically can access your Plesk control panel at the following address:
example.com with your own domain name or your website's IP address.
Domain Not Pointed or Working
If your domain name is not pointed to your hosting account yet, you will need to use your website's IP address instead of your domain name.
192.0.2.42 with your own website's IP address.
If these do not work, you will need to contact your hosting provider to get the proper link.
One you have the correct URL to log into, you can log into your Plesk control panel.