FGD you are in a similar place to me...
I'm first going to try using the DB I currently have, hopefully get it working then run any updates.
IF that doesn't work, then I'll upload a new install and overwrite the files needed [sounds more complex

]
As for the php malarkey, you will find phpMyAdmin quite straight-forward [for simple things] a friend showed me how to do the basics, so if you have a course lined up you should sail through it.
My host allows me to do a back-up through their cpanel system.
I had used a different CMS system before that also used these 'temp' files as mentioned is this post. When I had move that site, it was these files that caused the problems.
As mentioned by wishbone, delete these files, before you back up etc. Could this be the problem you had?
I've had some changes to do on my site, so the move has been put back, I'll post here once I've done it. It may help other noobs, like myself.
w