db-config.php file…where does it reside?

So unfamiliar as I am with some of this, the install instructions say:

You need to add the global table lines to db-config.php BEFORE installing Anti-Splog plugin or running the sql.txt

I nosed around, searched some, etc. Anyway, before I ask my host if that is something he has to do I want to ask here. Please advise at your convenience . Thx