Hi Fireman26 , after selecting "Open file", a folder will open. This could be the most recent folder opened, which may be c:\Premier. This folder, or whatever folder appears, may contain your company data file.
If you can see that file, and it is recent, select it and click Open. (It will have a .prm extension).
You will then see a window asking for a user name and password. The default user name is Administrator, and the default password is blank. Try logging in like that and see if your file opens.
If it does, great! Then go to Set-up (top menu) and company information, and make a note of the serial number (top left, 12 digit number starting 61). Now you have what you need to call MYOB about an upgrade.
If the file does not open with a blank password, then a password must have been created. Do you have a record of that?