You will need to enter the information about the database you will use for Joomla! now. It was suggested to write this information down under "Prepare for Install" tab. You may also read or review Creating a Database for Joomla!.

For simplification, these intructions are a reference to installing with a MySQLi database. The instructions on the installation page are self explanatory, but here they are again:

• Database Type: MySQLi is the common database used
• Hostname Where is your database located? Common is localhost, but some hosts use a specific database server such as dbserver1.yourhost.com
• Username: the username used to connect to the database
• Password: the password for the database's username
• Database Name: the name of the database
• Table Prefix: one is generated automatically, but you can change it. For example, jos3_ can be used. Just don't forget to put the underscore character (_) at the end of the prefix.
• Old Database Process: should the installer backup or delete existing tables during the installation of new tables? Click, Yes or No to select the choice.

All these choices can be edited on the Site Global Configuration page, under Server options after the installation is completed. Note, you will break your installation if you change these settings after installation unless you have a complete copy of the current database being used by the Joomla! installation. Common uses would be to update the username and password of the database or to complete a move of an existing installation to a new host with different parameters.