Welcome to Just Answer and thanks for your question. I am assuming by a "file' you mean the sum of your research. Do you still have the old computer from which you saved your family file? In that case , save the file again as a GEDCOM file. All versions of Family Tree Maker will read a GEDCOM.
To upgrade Family Tree Maker, go to http://www.genealogy.com/soft_ftm.html
The new software is $39.95.
Let me know if this doesn't solve your problem.
Yes, I have the old computer and I have two backup floppies. Have been working with the CEDCOM changes on the old computer (source) while turned on to the old Family Tree Maker. Am not sure if this is correct? Then when finished will backup floppy from the old computer and install the backup floppy to the newer computer and Family Tree Maker. Again, Do I use the source file (the old computer) and change it to GEDCOM. and then save or backup the old computer file on a floppy. Then save the backup floppy on the newer Family Tree Maker? Is it correct to make the CEDCOM changes on the old computer?
Hope that's not to confusing, rather repetitive.
Yes, it's fine to make the GEDCOM changes on the old computer. When you are done, you want to save the whole thing as a GEDCOM. You can then copy the GEDCOM from your floppy to the hard drive of your new computer. Remember to write down where you put it (i.e. c:\FTW\familyfile.ged). Then start up your Family Tree Maker program on the new computer. Go to "File" then "Open." All the way at the bottom, change the dropdown menu to GEDCOM. Then go to the top of the page where it says "Look in:" and tell it where to look for your GEDCOM. It will read your family file into the new computer.