4
Well when I look into your face, I can see that you are not dumb, just a newbie.
The mainfile contains the data for access to the database and XOOPS virtual and physical root path.
If you copy the mainfile of your local XOOPS to your host, you will see a blank page when you go to your site.
There are allready enough people who made this experience a few times (including me) and I tell you, it scares the s... out of you
Have a look at both the files, then you can see what I mean.
Success