First, a question:
Your MySQL database is on a machine that is in your location (or your want it to be) right?
The purpose of bigdump is to get backups/downloads doen through a browser. You don't need a browser to import your database (that's what that .sql file you have is is -- a series of SQL statements). Its just a big text file that is already right where it belongs -- on your machine! You can open it with a text editor (not notepad) and you will see... So this has nothing to do with bigdump.php, the Apache httpd.exe or any of that, this is a MySQL restoration.
your friends gave you the right syntax.
this page has a better explanation:http://www.velikan.net/import-sql-dump- ... -database/
The scenario: server crashes and you got mysql dump file stored on your hard drive. First you install mySQL database - then create database, database user and database password and then use next command line:
your command line:C:\xampp\mysql\bin\mysql.exe -u root phpbb_ < "C:\xampp\htdocs\phpbb2\dump\phpbb_db_backup.sql"
provided that phpbb_db_backup.sql file is already in htdocs\phpbb2\dump\
make sure your new database has the same name, user name and password as your old system.
As to the right order in which to reinstall your forum, I can't say, as I'm only expert with YaBB. Normally, you install the software, and then restore the backup. If that is also the case with phpBB2, then if you have installed the bulletin board, you are likely ready to restore the data.