I've read the tutorial and got no where... :(

This is my situation:
I've downloaded the .70 release wich i decompressed to a folder.

Now i have the updates from .71 to .78.
How to i correctly update the roms from .70?
Scan? Rebuild?
From what i saw on the .70 release ( from sharereactor) I think it's a split/merge edition
Thanks