Next we come to where you enter the connection information for your MySQL database. 

This tends to be one of the more confusing steps, but it really doesn't need to be.  All of the information for this page is somewhere within your hosting control panel.

Database Server
Odds are very good that you can leave this at the default 'localhost' and be fine.  However some large hosts, notably GoDaddy and StartLogic, host their web sites and database separately in which case you'll be given another host name to put in here. 

Username & Password
The username and password for your database are likely not the same as the login you use to get into your hosting control panel. When you setup your database you likely entered a username and password.  Sometimes the username and database name are the same.  And some hosts will assign the username and password for you.

If you are on a host that uses cPanel your database username includes your login as well, so if your cPanel login is bob and you make a database called buddy the username would be bob_buddy.

Database Name
This is the name you gave your database when you created it. 

Like the username, hosts using cPanel will append your login to the front of the database name as well.

Prefix
ProofBuddy uses 3 dozen database fields.  The prefix allows you to use an existing database without conflicting with any existing tables.  Your best bet is to just keep this at pb unless you have a good reason for doing otherwise.