At the end of the installation procedure, you should have been given the opportunity to run a "MySQL Server Instance Config Wizard." This sets up the mysql server to run and has a page where the password is created for root access.
If you did not run the config wizard at the time of installation, there is a shortcut to it on your start menu.
Once you have the server instance configured and the mysql server software is running, you will be able to connect using the mysql administrator.
If you are running the mysql administrator on the same computer with the mysql server software (which is the likely case), the information you enter will be -
Server Host: localhost
Password: the root password you entered in the config wizard