Larry -
Load your program into Mach 3. Go to "Edit G Code". This will open a window and put the program in the frame for editing.
You can then go to the top left hand corner (file) and "save as" - which will give you the oportunity to save the file with a different name, such as 'write2' or 'writelarry'. Make sure your GCode files are saved in the folder named Mach3/GCode otherwise Mach3 will not know where to look.
If you have saved files before and lost them, if you can remember the names, use the search facility in Windows to find the files. Once you have found them, note where they are, and open "Notepad". Recover them to notepad, using "open". Browse around until you find the files and using the "save as" facility in the same way, save them back to the GCode file.
If you then amend it in the editor to put the new name in, and "save" it will save it under the new name. Using "save" (not "save as") the file will be saved with the name at the top of the window, in the folder you got it from.
If your code does not work, post it, and I am sure someone will offer some help.