In some cases, it's necessary to simply insert the CD with the new version and the installer will do the rest if it finds another version of the same software installed on the PC. If this doesn't happen, then you need to manually launch the old version and export the data. You can either use File > Save as or File > Export to export the database to a location of choice.
After this operation, install the new version and use File > Open or File > Import.
Note: If the files don't share the same registry keys, it's possible to install both versions, then it's simpler to check all the supported files.