You should first backup your FTM 9 file. I don’t remember details about FTM 9 but run file compress and all other options that will check your file for errors. The cleaner your file is the easier the conversions will be. Take another backup of your FTM 9 file and keep a copy in a secure place, not on your hard drive. FTM 2012 will be able to read your FTM 9 file and create a new FTM 2012 file. You should create a folder where you want your FTM 2012 files to be and make sure the conversion process creates the upgraded file in that folder. This process will not change your FTM 9 file so you can always start over.
The user interface for FTM 2012 is different from FTM 9 so you will have a learning curve. You may want to export a small portion of your FTM 9 as a GEDCOM and import that into FTM 2012. You can then take the tutorials and learn how to use FTM 20102 before converting your main file.