Hi
First run a backup of the file you found to your hard-drive
File - backup
it will probably name your file with today's date
eg valry-2011-04-15.ftmb
it will also confirm where the working directory is
(so you can also check what is in there)
Probably c:\family tree maker\
However, change the file name to something like valry-mk2 before backing up.
Second run two exports (belt and braces)
File - export
run one export as a filemaker file
then another to a gedcom5.5 file
Ensure the file name is same as above ie valry-mk2
Then you can safely close FTM.
It should then save your file as valry-mk2.ftm on your hdd in the working directory above.
I think ...................

Ray