Kathleen, I assume that you followed the steps here:
http://modxcms.com/moving-sites-to-new-servers.html
If you can use the Manager at all, you are close.
The table prefix is just what you guessed. It’s so you can run two or more separate MODx sites on the same server. You can (and probably should) use the same table prefix on your local site and the remote duplicate of that site. It will make your life a lot simpler.
From the error message, I’d say that your problem is not the database. MODx can’t find an actual file on the server.
As you suspected, your file path settings in the File Manager tab and Interface & Features tab need correcting.
They should be the full physical path to those directories.
Do the File Manager one first, it should be something like this:
/home/your_user_name/public_html/test/ (That’s your username with the hosting service, not the DB or the MODx username)
You’ll know it’s right when you can browse the files successfully when you click on Manage Files on the Resources tab.
Once you have that, correct the one on the Interface & Features tab to match (plus /assets).