Hey,
When you open your tune file, all the menus under the "Navigator/File information" (Left window) relate to that file <main file>
Now when you open a compare file, you will get the prompt. If you select yes you will only be show different table under the compare menu.
Now the compare menu is under Change History, this will now be your furthest right heading....
As you can see it shows you in basic terms whats different from file to file.
In my case its only show's sections that are different as i clicked yes, if you select no you will get everything.
Now if you jump back to the left area and select a table you want to play with
For instance the fuel base - you can see next to history you can now select your tune / stock tune or the compare file.
You can only have one of these open at a time, but whitch-ever is open is the active one.
if you select your compare file - then select APPLY it will write the data from that file to your main file.
so that is one way to copy data from another tune file.
obviously you would need to save / upload to your car etc etc.
cheers, christian